Rachid Aït Mouss

Saida Krimi

Benoît Glorieux

Ismail Khattech

Michel Couzi

Thierry Cardinal

Abdelaziz El

Structural characterization and calorimetric dissolution behavior of Na 2 O-CuO-P 2 O 5 glasses

Keywords: Sodium copper phosphate, Glasses, Density, DSC, XRD, Raman, UV-visible, Heat of dissolution

Two series of glasses belonging to the ternary system Na2O -CuO -P2O5 where copper is introduced differently were synthesized by the conventional melt-quenching technique. Both series start from meta-phosphate composition NaPO3 (50Na2O-50P2O5). In the first series, the Na2O/P2O5 ratio is constant (Na2O/P2O5 = 1) and both Na2O and P2O5 oxides were replaced by copper oxide CuO: (50-x/2) Na2O -xCuO -(50-x/2) P2O5, 0 ≤ x ≤ 40. In the second series, the molar percentage of P2O5 is kept constant at 50 mol% and Na2O is replaced by CuO: (50-x)Na2O -xCuO -50P2O5, 0 ≤ x ≤ 50. The glasses of these two series belong respectively to NaPO3-CuO and NaPO3-Cu(PO3)2 lines of the ternary system. These materials were characterized by density measurements, differential scanning calorimetry (DSC), X-ray diffraction (XRD), Raman, diffuse reflectance and dissolution heat measurements carried out with micro-calorimetry technique. Introduction of copper in meta-phosphate glass induces a blue/green color, and strengthens the vitreous network, as shown by the decrease of the molar volume (VM) and the increase of the glass transition temperature (Tg) when the content of CuO rises. The crystallization of the glasses, followed by XRD, leads to the formation of NaPO3, Na2CuP2O7 or Na2Cu(PO3)4 depending on the composition. Raman spectroscopy shows the conservation of the metaphosphate chains for NaPO3-Cu(PO3)2 glasses characterized by a constant O/P ratio (O/P = 3) and the depolymerization of these chains for NaPO3-CuO glasses where O/P ratio varies from 0 to 3.67. UV -visible study showed that the optical energy gap decreases by increasing the CuO concentration. Calorimetric study of the dissolution of glasses in acid solution shows a decrease of the dissolution enthalpy, for both series, when the CuO content increases. The dissolution phenomenon is endothermic for glasses with low content in CuO (x < 30) and exothermic for glasses rich in CuO.

Introduction

It is known that phosphate glasses have become of great interest in recent times thanks to their specific physical and chemical unique properties that imply very different applications. We can name among these interesting properties the following: low glass transition temperatures, low melting and softening temperatures, high electrical conductivity and interesting dielectric properties [START_REF] Shash | Influence of lithium phosphate concentration and temperature on the electrical conduction of (76V2O5-24P2O5)1 -X(Li3PO4)X glasses[END_REF], large thermal expansion coefficients [START_REF] Wilder | Glasses and glass ceramics for sealing to aluminum alloys[END_REF], and also high optical transparency window over the UV, visible and infrared wavelength range [START_REF] Hsu | Effect of silver concentration on the silveractivated phosphate glass[END_REF]. All these properties make phosphate glasses interesting and useful materials candidates for a wide range of technical applications such as: high power laser devices [START_REF] Campbell | Nd-doped phosphate glasses for high-energy/high-peak-power lasers[END_REF], solid electrolytes [START_REF] Abe | Protonic conduction in alkaline earth metaphosphate glasses containing water[END_REF], biomaterials for neural repair [START_REF] Gilchrist | In vitro nerve repair-in vivo. The reconstruction of peripheral nerves by entubulation with biodegradeable glass tubes-a preliminary report[END_REF], tissue engineering [START_REF] Ahmed | Phosphate glasses for tissue engineering: part 1. Processing and characterisation of a ternary-based P2O5-CaO-Na2O glass system[END_REF], [START_REF] Ahmed | Phosphate glasses for tissue engineering: part 2. Processing and characterisation of a ternary-based P2O5-CaO-Na2O glass fibre system[END_REF], and bone fracture fixation [START_REF] Uo | Properties and cytotoxicity of water soluble Na2O-CaO-P2O5 glasses[END_REF]. However, glass technologists for a long time bypassed pure phosphate glasses because they usually have a relatively poor chemical durability in aqueous solutions. This major disadvantage is caused by the easily hydrolysable P-O-P bonds that are setup by the network former oxide P2O5 inside the glassy matrix. For this reason the addition of at least one network forming or modifying oxide as Al2O3, Ga2O3, Fe2O3, PbO, SnO, ZnO, etc., is suggested in order to overcome this weakness by providing more covalent bonds resistant to water attack [START_REF] Minami | Thermal expansion and chemical durability of phosphate glasses[END_REF]. The diverse properties and applications of phosphate glasses depend on their structure, which is based on the distribution of Q n tetrahedral units in the vitreous network (n varies from 0 to 3 and represents the number of bridging oxygen per PO4 tetrahedron). Connection of PO4 tetrahedra gives rise to different phosphate groups depending on the value of O/P ratio. So, the glass structure can be formed by a cross-linked network of Q 3 tetrahedra (vitreous P2O5, O/P = 2.5), infinite metaphosphate chains of Q 2 tetrahedra (vitreous NaPO3, O/P = 3), or by small diphosphate P2O7 2 -(Q 1 , O/P = 3.5) and monophosphate PO4 3 -(Q 0 , O/P = 4) anions [START_REF] Brow | Review: the structure of simple phosphate glasses[END_REF].

The oldest work on sodium copper phosphate glasses dates back to 1969, when Maekawa et al. studied the optical spectra and magnetic susceptibilities of different transition metal oxides in vitreous NaPO3. They concluded that most Cu 2 + ions coordinate six oxygen atoms in the copper phosphate glasses [START_REF] Maekawa | Optical spectra of transition metals in Na2O-P2O5 glasses[END_REF]. Since then, many other studies have been conducted on glasses belonging to the ternary system Na2O-CuO-P2O5. The glass formation zone of this system has been identified and studied with various characterization techniques. Thermal analysis has been performed by Differential Thermal Analysis (DTA) and showed that when replacing Na2O by CuO, the glass transition temperature Tg increases. Also according to dilatometry measurements the softening temperature Td and hardness are found to increase as the copper content increases, while the thermal expansion coefficient decreases. FTIR and XPS analysis suggest that the modification occurring on the structure can be explained by the formation of POCu bonds, which replace P-O-P and P-O-Na bonds. These new formed bonds are greatly influenced by the experimental conditions of the glass melting; indeed increasing melting time and melting the mixture in flowing oxygen atmospheres instead of air enhance this phenomenon. 31 P magic angle spinning nuclear magnetic resonance (MAS-NMR) spectroscopy showed that the phosphate chain length is shortened as the CuO content increases and that the formation of P-O-Cu bonds is easier in the polyphosphate glasses than in metaphosphate ones. FTIR and Raman spectroscopies confirmed the structure of phosphate species i.e. the infinite metaphosphate chains get depolymerized by addition of CuO. Simulation of EPR spectra of (50-x/2) Na2O-xCuO-(50-x/2) P2O5 (0 ≤ x ≤ 30) glasses showed that Cu 2 + ions occupy two sites: one of them is preponderant at low Cu content and the other is preponderant at high content of Cu. EPR parameters of site at low content are consistent with Cu 2 + in an elongated octahedron. However, the values of the orbital reduction factors, deduced from EPR and optical data, are consistent with Cu 2 + surrounded by four ligands [START_REF] Shih | Thermal and corrosion behavior of P2O5-Na2O-CuO glasses[END_REF], [START_REF] Shih | FTIR and XPS studies of P2O5 -Na2O -CuO glasses[END_REF], [START_REF] Shih | Effect of redox state of copper on the properties of P2O5 -Na2O -CuO glasses[END_REF], [START_REF] Shih | 31 P MAS-NMR and FTIR analyses on the structure of CuO-containing sodium poly-and meta-phosphate glasses[END_REF], [START_REF] Chahine | Effect of CuO on the structure and properties of (50 -x/2)Na2O-xCuO-(50 -x/2)P2O5 glasses[END_REF], [START_REF] Daoudi | EPR and magnetic susceptibility of Na2O-CuO-P2O5 glasses[END_REF].

In this paper, we report on two different series of glasses belonging to the ternary system Na2O-CuO-P2O5: (50-x/2) Na2O -xCuO -(50-x/2) P2O5 (0 ≤ x ≤ 40) and (50-x)Na2O -xCuO -50P2O5, (0 ≤ x ≤ 50) with x is the molar percent or [(0.5-x/2)Na2O-xCuO-(0.5-x/2)P2O5 (0 ≤ x ≤ 0.4) and (0.5-x)Na2O -xCuO -0.5P2O5, (0 ≤ x ≤ 0.5)] with x is molar fraction. The aim of the study is to investigate the evolution of the glass matrix structure, while introducing CuO, by different characterization methods: density measurements, Differential scanning calorimetry (DSC), X-ray diffraction (XRD), Raman and diffuse reflectance spectroscopies, and micro-calorimetry.

Materials and experimental procedures 2.1. Glass samples preparation

Analytical grade powders of sodium carbonate Na2CO3 (99%, Sigma Aldrich), copper oxide CuO (98%, Merck) and ammonium dihydrogen phosphate NH4H2PO4 (99%, Merck), were used as starting materials. The chemicals in appropriate amounts were thoroughly hand mixed in a porcelain mortar to obtain a homogenized mixture. The mixtures were subjected first to heat treatments between 200 and 600 °C, in a muffle furnace, to eliminate volatile species NH3, H2O and CO2. They were then melted in a platinum crucible, at temperatures within a range from 750 °C to 1050 °C depending on the glass composition, for about 30 min. The melts were then quenched to room temperature in air. Vitreous NaPO3 is colorless while glasses containing copper are colored. The color varies from blue to green (Fig. 1). After the preparation, each glass is annealed at Tg-20 °C, to remove internal stresses, and then stored in a desiccator in order to minimize water absorption. The crystallization of the synthesized glasses was done by heating bulk vitreous samples at their corresponding Tg + 40 °C temperature for 12 h. The obtained crystalline materials were ground and analyzed by XRD.

Characterization of the glasses

X-ray diffraction (XRD) measurements were done at room temperature with a powder diffractometer (PANalytical X'Pert Pro) using Cu Kα radiation. Data was collected from 10° to 70° 2θ with a step of 0.02 and a count time of 12 s.

The density (ρ) of each glass was determined by the Archimedes method using diethyl phthalate as immersion liquid. Three samples of each composition were analyzed and the average density is reported. The accuracy of the density measurements is about ± 0.03 g cm -3 . The molar volume (VM = M/ρ) of glasses was calculated from the density (ρ) and the molar mass (M) and its random error was retrieved considering the accuracy of the density measurements.

Differential Scanning Calorimetry (DSC) was used to determine the transition and crystallization temperatures (Tg, Tc). DSC curves of powders (30-40 mg), obtained by crashing the glasses, were recorded on a computerized system (DSC 404 PC from Netzsch Inc.), from ambient temperature to 600 °C, at a heating rate of 10 °C/min. The instrumental error of all measured values is ± 5 °C. The measurements were carried out in hermetically sealed aluminum pans. The glass transition temperature (Tg) was taken as the inflection point of the endothermic peak and the crystallization temperature (Tc) at the maximum of the exothermic peak.

The Raman spectra of the vitreous samples were recorded on a confocal micro-Raman Labram (Horiba/Jobin-Yvon) spectrophotometer with a backscattering mode at room temperature in the range 250-1400 cm -1 . The excitation source was a 532 nm continuous laser. A holographic Notch filter was used to reject the Rayleigh diffusion. The backscattered light was collected through a 100 × objective and selectively transmitted toward a cooled CCD detector.

The dissolution heat of the samples was measured on a Setaram Calvet C-80 μ-calorimeter. This latter is composed by a reference cell containing only the solvent, and a working cell which comprises an inferior compartment, receiving an amount of approximately 20 mg of the ground glass sample, and a superior compartment where 4.5 ml of the acid solution were introduced. These two compartments are separated by a metallic lid, which opens when the reaction starts and allows contact between the material and the attacking solution. Both of the cells are surrounded by high performance thermopiles allowing the detection of the heat flow that resulted from the dissolution of different samples of solids. The dissolution reaction of the vitreous powder samples in a nitric acid solution (9 wt%) was carried out at a fixed temperature (25 °C). The dissolution enthalpy was determined by integrating the surface of the raw signal taking into account the calibration coefficient which was determined in previous works [START_REF] Brahim | Etude cinétique et thermodynamique de la dissolution de la fluorapatite dans l'acide phosphorique[END_REF], [START_REF] Zendah | Synthesis, characterization and thermochemistry of acid attack of "B" type carbonate fluorapatites[END_REF]. The accuracy on those measurements was calculated using statistical model proposed by Pattengill [START_REF] Pattengill | Statistical significance of linear least-squares parameters[END_REF]. The random error of the dissolution heat was calculated considering five integrations of raw signal of the dissolution.

Diffuse reflectance spectra were recorded on powders, obtained by crushing the glasses, in the 250-750 nm range, using a spectrofluorimeter SPEX FL212 with a 450 W xenon lamp light source. The reflectance is measured in a synchronous mode and compared to black (toner powder) and white (MgO) references. The measurements were confirmed on selected samples by direct transmittance measurements obtained on a Carry-Varian 5000 performed on thin polished glasses.

Results and discussion

Two compositional series of sodium copper phosphate glasses were prepared and studied (Fig. 2). Line 1 summarizes the major interesting measured properties for all studied vitreous materials. All vitreous samples prepared were confirmed to be amorphous using XRD analysis. As seen in Fig. 3, the glassy behavior shows a broad hump at 2θ = 30-33°.

No peak corresponding to any crystalline material is observed. This indicates that all components have completely entered the glassy matrix. ) glasses, while the density increases and the molar volume decreases for both series, when CuO content rises. The variation of the molar volume is less important for the second series due to the increase of the molar mass of the glasses of this series (Table 1). The reticulation of the glass network induced by the decrease of the molar volume for both series of glasses is due to the replacement of Na-O bonds by the more covalent Cu-O bonds. The evolution of molar volume and density are in agreement with the results obtained by Chahine et al. [START_REF] Chahine | Effect of CuO on the structure and properties of (50 -x/2)Na2O-xCuO-(50 -x/2)P2O5 glasses[END_REF]. 2. The crystallization of (50-x/2)Na2O -xCuO -(50-x/2)P2O5 glasses with 0 ≤ x ≤ 30, leads to the formation of both NaPO3 [START_REF] Ondik | The structure of anhydrous sodium trimetaphosphate Na3P3O9 and the monohydrate Na3P3O9, H2[END_REF] and Na2CuP2O7 [START_REF] Etheredge | Synthesis of a new layered sodium copper (II) pyrophosphate, Na2CuP2O7, via an eutectic halide flux[END_REF] crystalline phases. For glass compositions with x ≥ 33.33, we observe mainly the crystallization of the diphosphate Na2CuP2O7. One notices that NaPO3 phase disappeared for 33.33Na2O-33.33CuO-33.33P2O5 (Na2CuP2O7) composition, indicating that at this level all metaphosphate chains were depolymerized into diphosphate groups. Crystallization of (50-x)Na2O -xCuO -50P2O5 (0 < x < 50)

Density and molar volume

Crystallization of the glasses

glasses leads to the formation principally of Na2Cu(PO3)4 [START_REF] Laügt | Structure cristalline du polyphosphate de cuivre-sodium CuNa2(PO3)4[END_REF] meta-phosphate phase together with some unidentified peaks (Fig. 9). Glasses of compositions 10Na2O -40CuO -50P2O5 and 50CuO -50P2O5 heated at their Tg + 40 °C temperatures remains amorphous. 3 summarizes the most important bands and their assignments.

spectroscopy

As expected, the Raman spectra of the mixed NaPO3-Cu(PO3)2 glasses (O/P = 3) corresponding to line (II) (Fig. 11) are dominated by the bands characteristic of glasses with metaphosphate composition, i.e. the strong bands at ~ 1170 cm -1 due to the symmetric stretching mode of the PO2 middle groups νs(PO2) and at ~ 685 cm -1 due to the symmetric stretching mode of the P-O-P bridges νs(POP) [START_REF] Chahine | Effect of CuO on the structure and properties of (50 -x/2)Na2O-xCuO-(50 -x/2)P2O5 glasses[END_REF], [START_REF] Laügt | Structure cristalline du polyphosphate de cuivre-sodium CuNa2(PO3)4[END_REF].

Note also in all spectra the presence of a band near 1270 cm -1 attributed to the asymmetric stretching mode of the PO2 middle groups νas(PO2) [START_REF] Massera | Effect of glass composition on the chemical durability of zinc-phosphate-based glasses in aqueous solutions[END_REF]. It is known that the structure of the Na2Cu(PO3)2 crystalline phase corresponding to the glass composition x = 25 is made of infinite metaphosphate chains [START_REF] Laügt | Structure cristalline du polyphosphate de cuivre-sodium CuNa2(PO3)4[END_REF], whereas the crystal with composition Cu(PO3)2 (x = 50) is made of four membered P4O12 cyclic units, i.e. it is more precisely described by the formula Cu2P4O12 [START_REF] Laügt | La structure crystalline du tétramétaphosphate de cuivre Cu2P4O12[END_REF]. Furthermore, a 31 P MAS-NMR study of this series of glasses has shown that for high Cu contents, the glass contains both -O-PO2-O (denoted as Q (2) ) P a g e | 11 middle groups and -O-PO3 (denoted as Q (1) ) end groups [START_REF] Shih | 31 P MAS-NMR and FTIR analyses on the structure of CuO-containing sodium poly-and meta-phosphate glasses[END_REF]. Note that the Q (2) species bear a charge of -1 and the Q (1) ones bear a charge of -2. Obviously, this is not compatible with the chain nor with the cyclic metaphosphate structural units that contain Q (2) species only. In order to conciliate the simultaneous presence of Q (1) and Q (2) species in a glass with a global metaphosphate composition, we suppose that charge equilibrium is realized by the presence of neutral "branching" groups O = PO3/2 (denoted as Q (3) ), such as those found in P2O5 and in the ultra-phosphates, according to the scheme: 2Q (2) ↔ Q (1) + Q (3) . Indeed, in the glasses with high Cu contents (33.33 ≤ x ≤ 50) two broad shoulders develop progressively on each side of νs(PO2), situated at ~ 1320 cm -1 and ~ 1050 cm -1 that we assign respectively to the stretching vibration ν(PO) of the branching units Q (3) and to the symmetric stretching vibration ν(PO3) in Q (1) end groups, respectively (Table 3). The presence of Q (1) and Q (3) species may also be due to slight departures of the experimental compositions from the metaphosphate composition, but they are not expected to be present simultaneously, since charge compensation would not be necessary in those cases. Therefore, we conclude that the presence of high CuO contents in meta-phosphates (line II) provokes a partial depolymerization of the phosphate chains, thus creating PO3 end groups compensated by the creation of Q (3) branching groups between chain fragments, thus insuring the reticulation of the glass network and providing new P O terminal sites, probably to accommodate a distorted octahedral environment of oxygen atoms around the Cu 2 + ions [START_REF] Laügt | Structure cristalline du polyphosphate de cuivre-sodium CuNa2(PO3)4[END_REF], [START_REF] Laügt | La structure crystalline du tétramétaphosphate de cuivre Cu2P4O12[END_REF].

The Raman spectra of (50-x/2)Na2O -xCuO -(50-x/2)P2O5 glasses (line I) show quite different shapes depending on the CuO content (Fig. 10). With increasing copper ions content in the NaPO3 glass matrix, we observe that the intensity of the two peaks around ~ 684 and ~ 1162 cm -1 together with the band near ~ 1270 cm -1 found in metaphosphate glasses, as mentioned previously (Table 3), decreases until disappearing at x ~ 25. From x = 25 mol% (i.e. the triphosphate composition), the spectra completely change their shape; new bands at 633, 745 and ~ 1042 cm -1 occur and grow in intensity as the CuO content further increases. The last two ones are assigned respectively to the symmetric stretching vibration P-O-P and to the symmetric stretching mode of non-bridging oxygen (PO3)sym (Q (1) species) in dimeric (P2O7) 4 -units. In other words, the introduction of a network modifier such as CuO into NaPO3 glass causes the depolymerization of the glass structure made of the infinite phosphate chains leading to a distribution of shorter chain length species down to the dimeric diphosphate composition occurring at x = 0.33. These results are consistent with those previously reported for similar polyphosphate glassy systems [START_REF] Oueslati | Structural and thermochemical study of Na2O-ZnO-P2O5 glasses[END_REF], [START_REF] Omrani | Structural investigations and calorimetric dissolution of manganese phosphate glasses[END_REF], [START_REF] Oueslati Omrani | Structural and thermochemical properties of sodium magnesium phosphate glasses[END_REF], [START_REF] Metwalli | Properties and structure of copper ultraphosphate glasses[END_REF], [START_REF] Ma | Structural study of Na2O-FeO-Fe2O3-P2O5 glasses by Raman and Mössbauer spectroscopy[END_REF] except that a well-defined band at 633 cm -1 is observed for x ≥ 0.25.

We assign this band at 633 cm -1 to the stretching like symmetric vibration of "square planar" CuO4/2 structural units that are evidenced for the first time in phosphate glasses. The oxygen atoms involved in these groups may pertain to different PO3 end groups of diphosphate anions, such as those existing in crystalline Na2CuP2O7 under the form of (CuP2O7)∞ anionic ribbons [START_REF] Etheredge | Synthesis of a new layered sodium copper (II) pyrophosphate, Na2CuP2O7, via an eutectic halide flux[END_REF]. Also CuO single crystals are formed by such CuO4/2 interconnected structural units that exhibit a characteristic Raman active symmetrical stretching-like mode at 630 cm -1 [START_REF] Goldstein | Raman study of CuO single crystal[END_REF]. So, we conclude that a reticulation of the glass network is achieved by the creation of Cu-O-P bridges between diphosphate groups. The glasses from the (50-x)Na2O -xCuO -50P2O5 series (0 ≤ x ≤ 50; line II) present a quite different aspect.

Diffuse reflectance study

The first sample of this series (x = 10) shows a broad transmission band, from 300 nm to 700 nm, with a light blue color. With the introduction of copper oxide, the transmission band edges narrow as they shift to 320 nm for the high energy edge and to 650 nm for the low energy edge. The color of the glasses is similar to the first series one. The substitution of Na2O by CuO induces a blue absorption and a maximum transmission at 540 nm, which corresponds to dark green glasses that gets darker as the CuO content increases.

It is known that copper takes an octahedral coordination. Thus, Cu 2 + in vitreous state produces a ligand field splitting of the free ion energy level. A tetragonal distortion of the octahedral coordination of Cu 2 + is induced by the Jahn-Teller effect due to the non-crystalline structural disorder [START_REF] Ravikumar | Tetragonal site of transition metal ions doped sodium phosphate glasses[END_REF]. This effect leads to an elongated tetragonal octahedral environment surrounding copper with four short bond lengths in the plane and two larger axial bond lengths. The splitting shifts then from octahedral to tetragonal, pyramid or square plane by increasing the crystal field.

The low energy absorption band located above 600 nm is attributed to the d-d electronic transition of Cu 2 + ion [START_REF] Singh | Comparative investigation on the effect of alkaline earth oxides on the intensity of absorption bands due to Cu 2 + , Mn 3 + and Cr 3 + ions in ternary silicate glasses[END_REF]. It is also found that this band shifted toward high energies as the amount of CuO increased. This behavior can be explained by an emphasis of the distortion, which leads to an increase of the splitting energy of the corresponding 3d level [START_REF] Maekawa | Optical spectra of transition metals in Na2O-P2O5 glasses[END_REF]. The high energy band below 300 nm is attributed to the O Cu charge transfer which corresponds to an electron transition between the 2p state of oxygen and the 3d state of copper [START_REF] Bae | Ultraviolet optical absorptions of semiconducting copper phosphate glasses[END_REF]. As it can be seen easily in Fig. 14, the gap between the two energy states decreases while increasing the CuO amount, which leads also to an increase of the related wavelength. This behavior, observed in several glass systems containing transition metal oxides, is attributed to the structural change in the glass network and the formation of non-bridging oxygen bonds [START_REF] Ouis | Structural and optical properties of CuO in zinc phosphate glasses and effects of gamma irradiation[END_REF]. Optical measurements, in the 750-2000 cm -1 domain and EPR spectra will be carried out to have more information on the coordination of copper ions.

Dissolution heat of glasses

Phosphate glasses are known to have a relatively poor chemical durability thus making them easily soluble in aqueous as well as acidic solutions. The microcalorimetric study undertaken consists on measuring dissolution heat of the different samples in a very specific solvent. The choice of the latter is determined by its ability to dissolve instantaneously the vitreous material without forming precipitates leading to thermochemical phenomena which also be detected by the calorimeter and then interfere with the desired measurement. After many attempts of dissolving an amount of studied glasses in many inorganic solvents (such as: H3PO4, HNO3, HCl), we observed that a 9% weight nitric acid (HNO3) solution is the best convenient for our analysis. During the dissolution process, the volume of the solvent is fixed at 4.5 10 -3 l of HNO3 (9%weight), in both compartments of the micro-calorimeter, and the mass of different samples close to 20 mg. Complementary experiments were realized for both series of glasses in order to determine the relative error on the integrated area, using a statistical calculation method developed by Pattengill [START_REF] Pattengill | Statistical significance of linear least-squares parameters[END_REF]. Table 4 reports the dissolution heat values of the investigated glasses. Fig. 15 shows the variation of the dissolution heat versus mol% of CuO for the two series of glasses.

Dissolution heat decreases gradually from 6.29 ± 0.03 kJ/mol to -8.65 ± 0.04 kJ/mol for (50-x/2) Na2O -xCuO -(50-x/2) P2O5 glasses and to -3.8 ± 0.2 kJ/mol for (50-x) Na2O -xCuO -50 P2O5 glasses. It is seen from these results that the dissolution phenomenon is endothermic for glasses with low content in CuO (x < 30) and exothermic for glasses rich in CuO. This change agrees well with the different measurements (Tg, density) made previously. Indeed we observed a strong modification in many properties around 30 mol% CuO. The evolution of the dissolution heat of Na2O-CuO-P2O5 glasses from endothermic to exothermic phenomenon is due to the modification of the vitreous network when CuO replaces Na2O. We can see that the dissolution heat is endothermic for glasses with weak bonds (-Na-O-P-linkages) and exothermic for glasses with strong bonds (-Cu-O-P-linkages). The decrease in the dissolution heat in acid solution shows a dependence of this quantity with the increasing covalent bonds in the network. These results are similar to those reported previously for Na2O-MO-P2O5 glasses (M Zn, Mn, Mg, Sr) [START_REF] Oueslati | Structural and thermochemical study of Na2O-ZnO-P2O5 glasses[END_REF], [START_REF] Omrani | Structural investigations and calorimetric dissolution of manganese phosphate glasses[END_REF], [START_REF] Oueslati Omrani | Structural and thermochemical properties of sodium magnesium phosphate glasses[END_REF], [START_REF] Cherbib | Structural and thermochemical study of strontium sodium phosphate glasses[END_REF].

Conclusions

The role of the copper oxide CuO was investigated for two glass series of the ternary system Na2O-CuO-P2O5, using various techniques: density measurements, DSC, XRD, Raman and diffuse reflectance. The evolution of density, molar volume and glass transition temperature versus CuO content implies the reticulation of the glass network due to the replacement of Na O bonds by the more covalent Cu-O bonds for both series of glasses. These results were confirmed by the Raman and reflectance diffuse spectroscopy studies. Indeed the reticulation of the glass network is achieved by the creation of Cu-O-P linkages. All results were correlated with dissolution heat measurements by micro-calorimetry. The dissolution enthalpy decreases, for both series, when the CuO content increases. This study showed also a transition between an endothermic behavior of the glass dissolution, observed for the glasses with lower CuO content, and an exothermic phenomenon that occurs around 30-33 mol% CuO, corresponding to an important modification of the vitreous network.

Fig. 1 .

 1 Fig. 1. Photographs of (50-x/2) Na2O -xCuO -(50-x/2) P2O5 (0 ≤ x ≤ 40) and (50-x) Na2O -xCuO -50 P2O5 (0 ≤ x ≤ 50) glasses showing the evolution of the color versus CuO content.

  (I) represents the compositions (50-x/2)Na2O -xCuO -(50-x/2) P2O5 (0 ≤ x ≤ 40) where CuO is added to NaPO3, x = 0 corresponds to the metaphosphate NaPO3 and x = 33.33 corresponds to the diphosphate Na2CuP2O7. An attempt to synthesize the glass with composition 25Na2O -50CuO -25P2O5 (NaCuPO4) was done, but it led to a crystalline product. Line (II) represents the compositions (50-x) Na2O -xCuO -50P2O5 (0 ≤ x ≤ 50) located between the two metaphosphate extremities NaPO3 and Cu(PO3)2 with the composition Na2Cu(PO3)2 (x = 25) in between. Table

Fig. 2 .

 2 Fig. 2. Compositions of (50-x/2)Na2O -xCuO -(50-x/2)P2O5 (0 ≤ x ≤ 40) (line I) and (50-x)Na2O -xCuO -50P2O5 (0 ≤ x ≤ 50) (line II) glasses in the Na2O -CuO -P2O5 ternary diagram.

Fig. 4

 4 Fig. 4 shows the variation of the molar mass (M), the density (ρ) and the molar volume (VM) versus CuO content, for both series of glasses. The molar mass M (M = xM(Na2O) + yM(CuO) + zM(P2O5), with the

Fig. 4 .P a g e | 7 3. 2 .

 472 Fig. 4. Evolution of molar mass (a), density (b), and molar volume (c) for (50-x/2)Na2O-xCuO-(50-x/2)P2O5 (Line (I)) (0 ≤ x ≤ 40) and (50-x)Na2O-xCuO-50P2O5 (Line (II))(0 ≤ x ≤ 50) glasses versus CuO mol%.

Fig. 5 .P a g e | 8 Fig. 6 .Fig. 7 .

 5867 Fig. 5. DSC thermograms for (50-x/2) Na2Ox CuO -(50-x/2) P2O5 (0 < x ≤ 40) glasses.

Fig. 8 ,

 8 Fig. 8, Fig. 9 show some XRD patterns, as examples, respectively for (50-x/2)Na2O -xCuO -(50-x/2) P2O5 (x = 20 and 33.33%) and (50-x)Na2O -xCuO -50P2O5 (x = 20 and 25%) glasses heated at Tg + 40 (°C) for 12 h. The identified crystalline phases from the annealed glasses are shown in Table2. The crystallization of (50-x/2)Na2O -xCuO -(50-x/2)P2O5 glasses with 0 ≤ x ≤ 30, leads to the formation of both NaPO3[START_REF] Ondik | The structure of anhydrous sodium trimetaphosphate Na3P3O9 and the monohydrate Na3P3O9, H2[END_REF] and Na2CuP2O7[START_REF] Etheredge | Synthesis of a new layered sodium copper (II) pyrophosphate, Na2CuP2O7, via an eutectic halide flux[END_REF] crystalline phases. For glass compositions with x ≥ 33.33, we observe mainly the crystallization of the diphosphate Na2CuP2O7. One notices that NaPO3 phase disappeared for 33.33Na2O-33.33CuO-33.33P2O5 (Na2CuP2O7) composition, indicating that at this level all metaphosphate chains were depolymerized into diphosphate groups. Crystallization of (50-x)Na2O -xCuO -50P2O5 (0 < x < 50)

Fig. 8 .P a g e | 10 Fig. 9 .

 8109 Fig. 8. X-ray diffraction patterns for glasses heated at Tg + 40 °C: (a) 40Na2O -20CuO -40 P2O5 (b) 33.33 Na2O -33.33CuO -33.33P2O5.

Fig. 10 ,

 10 Fig. 10, Fig. 11 show the experimental Raman spectra respectively for (50-x/2)Na2O -xCuO -(50-x/2)P2O5 (0 ≤ x ≤ 40; line I) and (50-x)Na2O -xCuO -50P2O5 (0 ≤ x ≤ 50; line II) glasses. Table3summarizes the most important bands and their assignments.

Fig. 10 .Fig. 11 .

 1011 Fig. 10. Raman spectra of (50-x/2) Na2Ox CuO -(50-x/2) P2O5 (0 < x ≤ 40) glasses.

Fig. 12 ,

 12 Fig. 12, Fig. 13 show the diffuse reflectance spectra, recorded in the 250-750 cm -1 range, respectively for (50-x/2)Na2O -xCuO -(50-x/2)P2O5 (line I) and (50-x)Na2O -xCuO -50P2O5 (line II) glasses. Both families of these glasses present comparable results; a broad visible transmission band for the low CuO content glasses, and a shouldered transmission by increasing the CuO amount with a more important transmission in the red range compared to the blue range. All the studied copper glasses revealed a total absorption in the UV and IR ranges. The transmission bands in the (50-x/2)Na2O -xCuO -(50-x/2)P2O5 glasses (0 ≤ x ≤ 40; line I) are almost similar, with a high energy edge around 340 nm and a low energy edge near 600 nm. The increase of CuO concentration in the glass-matrix leads to the increase of the intensities of absorption in the 400-550 range, and the color of the glasses turns from a royal blue (for x = 10) into a darker blue as the CuO amount increases. The glasses with x > 30 present a dark green color, which is related to the increase of the overall absorption and the apparition of an additional absorption band in the blue range (< 450 nm).

Fig. 12 .P a g e | 14 Fig. 13 .

 121413 Fig. 12. UV -Vis diffuse reflectance spectra of (50-x/2) Na2Ox CuO -(50-x/2) P2O5 (0 < x ≤ 40) glasses.

Fig. 14 .

 14 Fig. 14. Variation of optical band gap of (50-x/2)Na2O -xCuO -(50-x/2)P2O5 (0 < x ≤ 40) (line I) and (50-x) Na2Ox CuO -50 P2O5 (0 < x ≤ 50) (line II) glasses.

Fig. 15 .

 15 Fig. 15. Evolution of dissolution heat quantities of (50-x/2)Na2O-xCuO-(50-x/2)P2O5 (0 ≤ x ≤ 40) (line I) and (50-x)Na2O-xCuO-50P2O5 (0 ≤ x ≤ 50) (line II) versus CuO content. The line is drawn as guide to the eyes.

Acknowledgements

P a g e | 17

The authors acknowledge the Morocco-France cooperation (Volubilis Program MA/120/229) and AUF (PCSI 59113PS024) for the financial support.


Anne Baillot

Anne Baillot Die

Fantasiestücke Nach

Callots Manier

: Textgrundlage

Editorische Prinzipien

Betrifft Vor Allem Kreisleriana

N Hdbuch

Keywords: Textgrundlage, editorische Prinzipien, Textauswahl und relevante Themen Inhalt und Titelei 2. Die DKV-Ausgabe 3. Textauswahl Literaturverzeichnis 1. Ein programmatischer « doppelte Bezugnahme auf die Musik und die bildende Kunst als ästhetische Vorbilder » (Hdbuch, 9

Themenschwerpunkte -1-

Tout en tenant compte de la relative hétérogénéité, générique comme thématique, et de la spécificité de chacun des récits qui composent ce « journal d'un voyageur enthousiaste » que sont les Fantasiestücke in Callot's Manier, on abordera le recueil qui a fait le succès d'E.T.A. Hoffmann en interrogeant la fonction de ses grands thèmes et catégories structurants : notamment la problématique de l'artiste, la tension entre trivialité et idéalité, la réflexion sur les rapports entre arts et littérature, le merveilleux et le fantastique.

On accordera une attention particulière aux catégories esthétiques et littéraires qui, en référence à Jacques Callot, constituent la « manière » littéraire de l'auteur : l'humour, le grotesque, l'hétérogène, le bizarre et l'étrange, la place prépondérante accordée à l'imagination et à la subjectivité, ainsi que l'aptitude à faire apparaître les éléments du quotidien « sous le jour d'une certaine originalité romantique », comme Hoffmann l'écrit lui-même en parlant de Jacques Callot. On analysera la manière dont la complexité de l'économie interne des récits et l'ironie qui émane du jeu des perspectives narratives comme de l'intertextualité font surgir ces caractéristiques propres au romantisme hoffmannien.

  Dimension des Grotesken 1. Untertitel: Blätter aus dem Tagebuch eines reisenden Enthusiasten • « Janusköpfigkeit zwischen Romantik und Moderne » (Hdbuch, 10) • Enthusiasmus: Bezug zu Hoffmanns Beschäftigung mit der Psychologie Alle Texte wurden für die Auflage 1819 « durchgehend leicht bearbeitet, einige gestrafft und umgestellt. In fast allen Texten ist eine Reihe kleiner sprachlicher und stilistischer Änderungen zu finden. » (DKV, 557) • Einige orthographische Anpassungen, dennoch sind beide Ausgaben inkonsequent • Fremdwörter durch eingedeutschte/deutsche Wörter ersetzt = auffälligste Veränderung (tolerieren->dulden z.B.) • Längere Sätze geteilt, verschachtelte Sätze durch Umstellungen vereinfacht • Unklar, welche Rolle Hoffmann dabei gespielt hat (DKV, 558) Vieles in der dt Sprache im frühen 19. Jh noch nicht normiert • Hoffmann selbst kein großer Freund der Vereinheitlichung und der Normierung=> nicht in sich sprachlich und typographisch konsequent • Hoffmann war das egal, er autorisierte auch Druckversionen, wo stark in den Text eingegriffen wurde (Einfügung regionaler Bräuche z.B.)

	Die Fantasiestücke nach Callots Einleitend 1. Originalausgabe 1. … aber nach Callots Manier 1. Wirkung von Callots Manier lt. Hoffmann 2. Was enthält die DKV-Ausgabe 2. Überarbeitung Erstausgabe von 1814-1815 ->Auflage von 1819 -typographisch 2. Überarbeitung Erstausgabe von 1814-1815 2. Kritischer Apparat 2. Normalisierungen in der DKV-Ausgabe 2. Aufbewahrte Originalformen 2. Grenzen der Normierung 3. Textauswahl ->Auflage von 1819 -inhaltlich Manier: Textgrundlage, editorische Prinzipien, Textauswahl Februar 2021 Anne Baillot, Le Mans Université • Editionsphilologie als zentrale Dimension der Literaturwissenschaft • Betrifft den Umgang mit Handschriften (oft mehrere Abschriften vorhanden bzw. mehrere Bearbeitungen) sowie mit Drucken (unterschiedliche Ausgaben/Auflagen) • Etablierung der Textgrundlage soll objektiv sein und wird stringent begründet (lange Tradition der Editionskriterien und Editionstypen), unterliegt jedoch einer Interpretation (->Debatte um die Neutralität des Editors in der Editionsphilologie). Eckbegriffe: Orientierung am Befund, Behutsamkeit. • Digitale Methoden ermöglichen Zugang zu unterschiedlichen Formen des Textes; Beispiel Sandmann: https://www.berliner-intellektuelle.eu/manuscript?Sandmann+de#1 Prinzessin Blandina => Praxis, die für die Zeit nicht ungewöhnlich ist; Variationen in den Druckfassungen als kompositorische Entscheidungen zu interpretieren (kann in den Textkommentar einfliessen) • Als Pendant zu den Fantasiestücken im Titel • Jacques Callot: französischer Maler (1592-1635) • Vorbildfunktion des Malers in Stück 1 erklärt (in unserer Auswahl) • Liegt an: Strukturprinzip seiner Werke und darin enthaltene Ironie (DVK, 18). Beispiele hier zu finden (Bezug zu präzisen Werken im Hdbuch genau nachverfolgt): http://blog.bnf.fr/gallica/index.php/2012/11/14/la-numerisation-des-gravures-de-jacques-callot/ • Seine Zeichnungen sind « Reflexe all der fantastischen wunderlichen Erscheinungen, die der Zauber seiner überregen Fantasie hervorrief. » (DKV, 17) • Figuren, die sich in der Fantasie des Zuschauers einprägen • « Es ist die permanente Konfrontation zwischen heterogenen Welten Hdbuch, 10) ØAndererseits bis in den Wahnsinn hinein intradiegetische Positionierung => mehrfache Aufsplitterung der Erzählinstanz • « Blätter »: Hinweis auf Zersplitterung, Unordnung, Flüchtigkeit • Tagebuch: Ich-Perspektive • Enthält alle Werke Hoffmanns, chronologisch geordnet, in mehreren Bänden • Im Band enthalten: Fantasiestücke+ weitere kleine Schriften, die 1814 vor dem Umzug nach Berlin im Druck erschienen (DKV, 548) • Fantasiestücke werden hier nach der Erstausgabe herausgegeben: anders als andere Hoffmann-Ausgaben zuvor, die die 2. Auflage von 1819 bevorzugen (DKV, 549) • Fassung von 1814/15: schliesst erste Entwicklungsphase von Hoffmann ab+Version, die Hoffmann schlagartig berühmt gemacht hat (geringe Wirkung der Auflage von 1819; DKV, 559) => entstehungsgeschichtliche+wirkungsgeschichtliche Argumente • Veränderungen eindeutig von Hoffmann verantwortet • Besonders wichtig im Magnetiseur und in den Abenteuern der Sylvester-Nacht (-> immer im Apparat nach den Abweichungen nachschlagen; vgl. DKV 559 unten für die Abkürzungen um die Angaben zu verstehen) • Lesart = unterschiedliche Fassungen eines Textes, bezogen auf eine spezifische Textstelle (https://www.duden.de/rechtschreibung/Lesart) • Streichung des Schauspiels Prinzessin Blandina • Abweichungen in Auflage von 1819 werden signalisiert • Nur Kurzfassung der editorischen Prinzipien in unserem Band aufgeführt (S. 549-551) • Desweiteren in der DKV-Ausgabe: Entstehung, Quellen, • Einhalten der Eigenart der Sprache und Schreibweise Hoffmanns als (immer sofern keine Mißverständnisse dadurch entstehen) • Oberbegriff: « Le récit romantique » oberstes Prinzip, aber: • Groß-und Kleinschreibung, Getrenntschreibung, Zeichensetzung • Les épreuves porteront uniquement sur les sections I, II, IV, V, VI, VII, • Normalisierung in der Graphie außer in den Fällen, wo es die • Syntax: Original behalten auch bei heute abweichender Verwendung VIII. La préface de Jean Paul ne fera pas partie des textes retenus pour Aussprache verändert • Anredeformen: nach heutigen Regeln vereinheitlicht von Dativ und Akkusativ, sowie für eine Reihe von Flexionsformen l'explication de texte à l'oral mais sera supposée connue des (insbes. bei Adjektiven) candidats. Biographischer Hintergrund, Selbstzeugnisse, Wirkung (bezieht sich ausschließlich auf die zeitgenössische Rezeption), sowie Stellenkommentar • Anführungszeichen: fehlende öffnende oder schliessende Anführungszeichen hinzugefügt (aber nicht wenn sie ganz fehlen) • Auszeichnungen (gesperrt, kursiv,…) nur dann übernommen, wenn sie eine Hervorhebung anzeigen (also nicht bei Eigennamen)-> durch Kursivierung wiedergegeben • Schreibung von Fremdwörtern beibehalten sofern damals noch als Fremdwort empfunden • Historische Eigennamen auch nach der Vorlage • Getrenntschreibung beibehalten (z.B.: Tags über) • Interpunktion beibehalten, damals viel freier als heute • I Jacques Callot / II Ritter Gluck / IV Don Juan / V Nachrichten von den Þwenn man den Text der Fantasiestücke zu stark normiert, « verfehlt » neuesten Schicksalen des Hundes Berganza / VI Der Magnetiseur / VII man « die Eigenart des Dichters » (DKV, 551) Der Goldene Topf / VIII Die Abenteuer der Sylvester-Nacht Daher behutsame Behandlung von Druckfehlern (werden nicht systematisch « korrigiert ») -> schließt musikspezialisierte Stücke aus (« Kreisleriana »)

Cours de préparation à l'option littérature de l'agrégation d'allemand • Fantasiestücke erschienen bei Kunz in Bamberg 1814/1815 • 4 Bände • Enthalten einige Texte, die im Vorfeld bereits separat gedruckt worden waren (auch wenn für die Fantasiestücke konzipiert) -> betrifft vorrangig musikalische Stücke (nicht in unserer Auswahl) • Ein Stück der Erstausgabe in der 2. Auflage 1819 nicht mehr zu finden: (einer idealisierten Welt der Kunst und der banalen bürgerlichen Lebensrealität), die die Erzählungen der Fantasiestücke bestimmt und in der Gesamtanlage zur wechselseitigen Relativierung beider Sphären führt » (Hdbuch, 10) • ØEinerseits moderne Erzählweise: extradiegetischer Erzähler, beschaulicher Betrachter, ästhetischer Kritiker (Rolle des Kapellmeisters Johannes Kreisler als Rahmenerzähler der Kreisleriana, « selbst eine Art reisender Enthusiast », • •

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