A Sivakumar

P Shailaja

M Nandhini

S S Jude Dhas

R S Kumar

Abdulrahman I Almansour

Natarajan Arumugam

Shubhadip Chakraborty

S A M Britto Dhas

S Sahaya

Jude Dhas

Raju Suresh Kumar

S A Martin

Britto Dhas

Ternary switchable phase transition of CaCO3 by shock waves

Keywords: CaCO3, Shock waves, Order -disorder phase transition, Switchable phase transition

de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Introduction

A few well-known materials under various physical conditions can reveal remarkable surprises of hidden facts as and when persistent observations are being carried out. Exploring J o u r n a l P r e -p r o o f 2 phase change behavior of materials at high-pressure and high-temperature conditions is a fascinating journey for the researchers as it consistently provides new information on the crystallographic structures and their functions in accordance with various ranges of applied pressure and temperature. In recent years, searching for new phase change materials (crystalcrystal, crystalamorphous and amorphouscrystal) has attained a tremendous momentum due to their remarkable applications in various fields cutting across all the branches of science. These materials can give rise to outstanding performances which depend on their specific solid-state crystallographic phase that exists at a particular physical condition. Moreover, such kinds of phase transition experiments conducted on materials have significant academic as well as industrial importance due to their potential contribution for spectacular applications. Over the years, phase transition of several crystalline and noncrystalline materials have been extensively studied experimentally at static high-pressure, dynamic high-pressure, high-pressure compression and dynamic shock wave loaded conditions which have resulted in a variety of phase transitions routes that include forward and backward phase transition giving rise to crystal-crystal, amorphous-crystal and crystal-amorphous phase transitions [START_REF] Zhang | Materials discovery at high pressures[END_REF][2][START_REF] Su | Shock Wave Chemistry in a Metal-Organic Framework[END_REF][START_REF] Daia | Pressure-induced irreversible amorphization and metallization with a structural phase transition in arsenic telluride[END_REF][START_REF] Dai | Pressure-induced irreversible metallization accompanying the phase transitions in Sb2S3[END_REF][START_REF] Kang | Pressure-Induced Phase Transition in Hydrogen-Bonded Supramolecular Structure: Ammonium Formate[END_REF]. Apart from the above-mentioned phase transitions, switchable phase transition has also been observed which is always considered as the special case among the phase transitions. On the one hand, reversible phase transition is quite common in static pressure compression experiments [START_REF] Wełnic | Reversible switching in phase-change materials[END_REF][START_REF] Fan | Reversible Phase Transition of Porous Coordination Polymers[END_REF][START_REF] Andrzejewski | Reversible Pressure Preamorphization of a Piezochromic MetalOrganic Framework[END_REF][START_REF] Bennett | Reversible pressure-induced amorphization of a zeolitic imidazolate framework (ZIF-4)[END_REF][START_REF] Tashiro | Stress-Induced Reversible Phase Transition of Poly(tetramethylene naphthalate)[END_REF][START_REF] Wang | High-Pressure-Induced Reversible Phase Transition in Sulfamide[END_REF]. On the other hand, reversible crystallographic phase transition occurring at dynamic shock wave loaded conditions is quite unusual because there is no apparent report available on it in the literature, to date, at shocked conditions. Calcium carbonate (CaCO3) has been chosen for the experimental investigation because of the possible crystallographic phase transition that it might undergo at shocked conditions.

Being one of the standout polymorphic minerals present on the earth, it has occupied a wide range of coverage in the literature wherein the experimental details of the obtained high-pressure polymorphic phases have been documented over the period of the past 80 years [START_REF] Németh | A nanocrystalline monoclinic CaCO3 precursor of metastable aragonite[END_REF][START_REF] Bodnarchuk | Response of Calcium Carbonate Nanoparticles in Hydrophobic Solvent to Pressure, Temperature and Water[END_REF][START_REF] Ishizawa | Structural evolution of calcite at high temperatures: Phase V unveiled[END_REF]. Hence, it could be possible via experimentation to get a deep understanding of the mechanism of polymorphic phase transitions with respect to pressure and temperature. Furthermore, there are possibly two major reasons in choosing the material for the present shock wave recovery experiment in which the first reason is that it is essential to understand the earth minerals in J o u r n a l P r e -p r o o f 3 terms of global carbon recycle process with respect to the existing pressure and temperature as carbonates (CaCO3 and MgCO3) hold a major role in the processes of global carbon recycling and climate changes [START_REF] Yao | Novel highpressure calcium carbonates[END_REF][START_REF] Gavryushkin | Aragonite-II and CaCO3-VII: New High-Pressure, High-Temperature Polymorphs of CaCO3[END_REF]. Secondly, it has a variety of applications in catalysis, ceramics, electronics, pigments, medicine, cosmetics, etc [START_REF] Abdolmohammadi | Enhancement of J o u r n a l P r e -p r o o f Mechanical and Thermal Properties of Polycaprolactone/Chitosan Blend by Calcium Carbonate Nanoparticles[END_REF][START_REF] Trushina | CaCO3 vaterite microparticles for biomedical and personal care applications[END_REF]. CaCO3 has various crystallographic phases such as calcite (R C), aragonite (Pmcn), and vaterite (P63/mmc) which are the primary crystallographic phases and high-pressure distorted phases that are also available such as calcite-I, calcite-II, calcite-III, calcite-IV, calcite-V, aragonite-I, aragonite-II, post-aragonite, etc [START_REF] Simon | Structural Variations in Carbonates[END_REF].

Calcite is the stable crystallographic phase at room temperature and aragonite is the highpressure crystallographic phase, and vaterite is called the meta-stable phase with respect to calcite. Among the listed CaCO3 polymorphs, calcite is the most technologically important material and a thermodynamically stable material at ambient pressure. It is abundantly available in nature on the earth's surface. Interestingly, calcite has five crystallographic phases such as Calcite-I (R C), Calcite-II (P21/C), Calcite-III (C2/Cm/P-1), Calcite-IV (disorder phase), and calcite-V (disorder phase) in which calcite -IV and calcite -V are represented as high-pressure phases [START_REF] Simon | Structural Variations in Carbonates[END_REF][START_REF] Sergey | Raman spectroscopy and X-ray diffraction of sp3-CaCO3 at lower mantle pressures[END_REF][START_REF] Hagiya | The crystal data and stability of calcite III at high pressures based on single-crystal X-ray experiments[END_REF]. So far, several materials science and geological researchers have investigated and found crystallographic phase transitions in calcite with respect to pressure using static pressure compression and dynamic pressure compression experiments [START_REF] Simon | Structural Variations in Carbonates[END_REF][START_REF] Sergey | Raman spectroscopy and X-ray diffraction of sp3-CaCO3 at lower mantle pressures[END_REF][START_REF] Hagiya | The crystal data and stability of calcite III at high pressures based on single-crystal X-ray experiments[END_REF]. The first phase transition route from calcite I-II and calcite II-III phase transitions were observed at 1.5 GPa and 2.5 GPa pressure, respectively, by Bridgman in1938 [START_REF] Bridgman | The high pressure behavior of miscellaneous minerals[END_REF]. Followed by his publication, many researchers have observed the similar phase transitions at more are less the same pressure ranges [START_REF] Simon | Structural Variations in Carbonates[END_REF][START_REF] Davis | X-ray Diffraction Data on Two High-Pressure Phases of Calcium Carbonate[END_REF][START_REF] Joseph | The crystal structure of calciteIII[END_REF]. In addition to that, the following publications show that calcite-III b is obtained at 3.1 GPa while calcite-IV and calcite -V are found to be highly disordered structures and they represent high-pressure phases [START_REF] Merlini | Evidence of interspersed co-existing CaCO3-III and CaCO3-IIIb structures in polycrystalline CaCO3 at high pressure[END_REF]. Redfern reviewed clearly the high-pressure phase transitions of CaCO3 in the year 2000 [START_REF] Simon | Structural Variations in Carbonates[END_REF]. It is known from the literature that many of the researchers have anticipated the phase transition route from calcite-I-II-III which could be reversible [START_REF] Simon | Structural Variations in Carbonates[END_REF][START_REF] Bridgman | The high pressure behavior of miscellaneous minerals[END_REF] whereas none of them could provide the experimental evidence. Interestingly, Tyburczy and Ahrens et al have demonstrated the shock wave compression phase transition from calcite II-III at 2.5 GPa and calcite III-II which has been observed during the release of shock pressure [START_REF] James | Dynamic compression and volatile release of carbonates[END_REF].

In 1994, Guillaume Fiquet et al revealed the reversible phase transition from Calcite-I to Calcite-III and Calcite-III to Calcite-I wherein the critical phase transition was observed at 4.1

J o u r n a l P r e -p r o o f

GPa [START_REF] Guillaume | High-pressure X-ray diffraction study of carbonates: MgCO3, CaMg(CO3)2, and CaCO3[END_REF]. There is no report found, to date, on the dynamic shock wave induced phase transition for CaCO3. Reversible magnetic phase transition has been obtained for ZnFe2O4 and Co3O4 nanoparticles such that ZnFe2O4 nanoparticles exhibit the phase transition of paramagnetic to super-paramagnetic behavior [START_REF] Mowlika | Shock wave-induced switchable magnetic phase transition behaviour of ZnFe2O4 ferrite Nanoparticles[END_REF] while Co3O4 nanoparticles undergo super paramagnetic to paramagnetic phase transition with respect to the number of shocks [START_REF] Sivakumar | Shock Wave Driven Solid State Phase Transformation of Co3O4 to CoO Nanoparticles[END_REF]. More recently, switchable crystallographic phase transition has been observed in potassium sulfate crystals with respect to the number of shocks [START_REF] Sivakumar | Switchable Phase Transformation (Orthorhombic -Hexagonal) of Potassium Sulfate Single Crystal at Ambient Temperature by Shock Waves[END_REF].

The present experimental analysis is to verify whether the switchable crystallographic phase transition of CaCO3 by the dynamic impact of shock waves is achievable or not.

Moreover, high-pressure chemistry consistently offers significant new information and numerous unexpected results of various compounds on experimentation. Hence, the investigation of the impact of shock waves on CaCO3 is necessary to check whether there is a possibility to obtain additional unknown carbonate structures or not and the relative crystallographic structural stability of carbonates in a highly fluctuating environmental condition is essential as it is yet to be assessed.

Experimental section

Commercially available calcium carbonate (CaCO3) (Sigma Aldrich) was used for the shock wave recovery experiment. Before the shock wave loading, the title compound was calcinated at 500° C for purification and it was sent for the fine grinding process so as to obtain fine nanopowder. Then, it was divided equally into five samples to be used for the experimental analysis. Among the five samples, one sample was kept as the control sample and the remaining four samples were sent for experimentation so that different numbers of shock wave loadings such as 50,100,150 and 200 pulses could be exposed. The required shock waves have been generated by an in-house tabletop semiautomatic shock tube which is capable of producing shocks up to Mach number 5. The shock tube has three sections such as driver, driven and diaphragm sections which are made of seamless steel. The driver and driven sections consist of long tubes of 48 cm and 180 cm, respectively and both have an inner diameter of 1.5 cm.

Atmospheric air has been used as the input source for the required shock wave generation. While the atmospheric air is compressed into the driver section, at the critical pressure, the diaphragm J o u r n a l P r e -p r o o f is ruptured and the shock wave is generated and moves along the driven section. The detailed mechanism and working methodology of the pressure driven shock tube is discussed in our previous publication [START_REF] Sivakumar | Measurement of "Shock Wave Parameters" in a Novel Table-Top Shock Tube Using Microphones[END_REF]. For the present experiment, the shock waves of Mach number 2.2 with the pressure of 2.0 MPa and the temperature of 864 K have been used. The test samples have been placed one by one with the required interval between them in the sample holder which is typically placed 1cm away from the open end of the shock tube. Subsequently, 50,100,150 and 200 shock pulses have been loaded on the respective test samples with an interval of 5 sec between each shock pulse. For example, 50 pulses mean shock wave-exposed on a sample 50 times with Mach number 2.2. After the completion of the shock wave loading, the control and shock wave loaded samples have been analyzed by powder XRD and FTIR studies so as to understand the role of shock waves on CaCO3. The schematic diagram of the semi-automated pressure-driven shock tube has been showcased in our previous publication [START_REF] Kalaiarasi | Shock wave induced anatase to rutile TiO2 phase transition using pressure driven shock tube[END_REF].

Results and Discussion

Powder XRD results

A powder X-ray diffractometer (Bruker X-ray Diffractometer) has been utilized to evaluate the impact of shock waves on CaCO3 NPs. Before discussing the shock wave induced effects on the test sample, it is quite mandatory to confirm the phase formation and their diffraction angle positions of the test sample (calcinated at 500° C) so that the corresponding XRD pattern is presented in Fig. 1 along with the standard Calcite-I powder XRD pattern (ICSD: 20179). As seen in Fig. 1, the XRD pattern of the test sample and the simulated XRD pattern are found to be well corroborated. But, the calcinated powder sample exhibits a slightly higher angle shift from the original positions and such kinds of shifts are highly usual in high-temperature experiments which occur due to thermal softening. The observed diffraction peaks are indexed using the standard pattern of JCPDS card no 47-1713 and the indexed diffraction peaks are (012), (104), (110), (113), (208) (018) and (116). Among the observed diffraction peaks, (104) is the strongest diffraction peak which is the characteristic peak of calcite CaCO3 (trigonal -Rhombohedral structure) [START_REF] Suito | Phase relations of CaCO3 at high pressure and high temperature[END_REF] and the calculated unit cell values are a=4.980, b=4.980, c= 16.862 Å and V= 360 Å 3 , respectively. From the observed X-ray diffraction pattern of the control sample, it is clear that the synthesized CaCO3 NPs belong to the calcite phase wherein no mixed phase is J o u r n a l P r e -p r o o f found during the calcination process. Based on the assessment of the previous reports, the calcite phase is represented as calcite-I [START_REF] Guillaume | High-pressure X-ray diffraction study of carbonates: MgCO3, CaMg(CO3)2, and CaCO3[END_REF][START_REF] Suito | Phase relations of CaCO3 at high pressure and high temperature[END_REF]. Suito et al [START_REF] Merlini | Evidence of interspersed co-existing CaCO3-III and CaCO3-IIIb structures in polycrystalline CaCO3 at high pressure[END_REF][START_REF] Kalaiarasi | Shock wave induced anatase to rutile TiO2 phase transition using pressure driven shock tube[END_REF]. Moreover, several high-pressure single crystal experiments have revealed the reduction of cell volume during the Calcite I-II phase transition [START_REF] Simon | Structural Variations in Carbonates[END_REF][START_REF] Guillaume | High-pressure X-ray diffraction study of carbonates: MgCO3, CaMg(CO3)2, and CaCO3[END_REF]. In the present experiment, it is observed the higher angle shift of (104) 29.6 to 29.8 degree of crystalline peak which indicates the reduction of cell volume. The higher angle shift represents the compression of unit cells and the bond lengths of CaCO3. Furthermore at 100 shocks loaded conditions, the diffraction peaks get higher angle shift and interestingly the observed diffraction peak positions J o u r n a l P r e -p r o o f are found to be corroborated with the Calcite -III phase in accordance with the publications of Davis (1964) and Guillaume Fiquet et al (1994) [START_REF] Davis | X-ray Diffraction Data on Two High-Pressure Phases of Calcium Carbonate[END_REF][START_REF] Guillaume | High-pressure X-ray diffraction study of carbonates: MgCO3, CaMg(CO3)2, and CaCO3[END_REF]. Calcite -III phase has the characteristic peak of (220) at 30.02 degree. Moreover, as per the above-mentioned reports, Calcite -III has a higher disorder as compared to Calcite-I and Calcite -II. According to the literature reports, it is also observed diffraction peaks of less intensity and higher broadening peaks at 100 shocks loaded a condition which is a reliable proof for the higher disorder phase than that of calcite-I and II. Hence from the observed XRD results, J o u r n a l P r e -p r o o f it is clear that, the test sample of Calcite is phase transformed from Calcite -I to Calcite -II and Calcite -II to Calcite -III at 50 and 100 shocks loaded conditions, respectively. The observed phase transition route from Calcite -I-II-III is found to be well corroborated with the reported high-pressure calcite phase transitions [START_REF] Davis | X-ray Diffraction Data on Two High-Pressure Phases of Calcium Carbonate[END_REF][START_REF] Guillaume | High-pressure X-ray diffraction study of carbonates: MgCO3, CaMg(CO3)2, and CaCO3[END_REF][START_REF] Kalaiarasi | Shock wave induced anatase to rutile TiO2 phase transition using pressure driven shock tube[END_REF]. Rotation of oxy-anions and displacements of cations are involved during the phase transitions and in each case, the degree of rotation and displacement is significantly varied. The detailed mechanisms of these phase transitions are to be discussed in the later sections. Furthermore, the number of shock pulses is increased to 150 and 200 shocks to get the possible understanding of the phase diagram of the calcite phase with respect to the number of shock pulses as found in pressure-temperature phase diagram of the calcite [START_REF] Davis | X-ray Diffraction Data on Two High-Pressure Phases of Calcium Carbonate[END_REF][START_REF] Guillaume | High-pressure X-ray diffraction study of carbonates: MgCO3, CaMg(CO3)2, and CaCO3[END_REF][START_REF] Suito | Phase relations of CaCO3 at high pressure and high temperature[END_REF]. Before recording the XRD measurements of samples, it has been anticipated either to get Calcite III b phase or Calcite-IV phase at 150 and 200 shocks, respectively as obtained in the case of static high-pressure experiments [START_REF] Suito | Phase relations of CaCO3 at high pressure and high temperature[END_REF][START_REF] Liu | High-pressure compressibility and vibrational properties of (Ca,Mn)CO3[END_REF].

On the other hand, fascinating results of calcite have been obtained quite unexpectedly such that 150 and 200 shocked samples have exhibited calcite -II and Calcite-I phases, respectively and the corresponding XRD patterns are presented in Fig. 2. Interestingly, this happens to be the spectacular phase transition route as compared to the so far reported shock wave induced phase transitions as well as static high-pressure phase transitions of CaCO3 [START_REF] Sivakumar | Shock Wave Driven Solid State Phase Transformation of Co3O4 to CoO Nanoparticles[END_REF][START_REF] Sivakumar | Measurement of "Shock Wave Parameters" in a Novel Table-Top Shock Tube Using Microphones[END_REF][START_REF] Suito | Phase relations of CaCO3 at high pressure and high temperature[END_REF][START_REF] Liu | High-pressure compressibility and vibrational properties of (Ca,Mn)CO3[END_REF]. For a better understanding of peak shifting and peak broadening of the characteristic crystalline peaks of (104) and (113), zoomed-in version of the respective XRD profiles are presented in Fig. 3 and Fig. 4 by which it is clear that the control and 200 shocked samples belong to calcite-I whereas 50, as well as 150 shocked samples, belong to Calcite-II phase while 100 shocks loaded sample is identified with calcite-III phase. As seen in Fig. 3 and Fig. 4, it is very clear that there is a significant difference in diffracted peak positions of ( 104) and (113) peaks of the control calcite-I and shock wave induced calcite-I. From the overall observation of XRD measurement, it is obvious that the test sample of CaCO3 has undergone the switchable phase transition route of Calcite-I-II-III-II-I with respect to the control, 50,100,150 and 200 shocks loaded conditions. Note that it is probably the first observation of such kind of ternary switchable phase transition occurring between three phases of calcite. For a better understating of the ternary phase transition, the XRD patterns of simulated and 200 shocks loaded Calcite-I are presented in Fig. 6 wherein both the XRD patterns are found to be well corroborated such that the ternary phase transition is confirmed. The mechanism of the phase transitions is discussed in the following sections. The grain sizes are found to be 73, 66, 59, 64, 52 nm for the control, 50,100, 150, and 200 shocked samples, respectively. [START_REF] Simon | Structural Variations in Carbonates[END_REF][START_REF] Bridgman | The high pressure behavior of miscellaneous minerals[END_REF]. The space group (R C) is allowed to tilt slightly from the planer oxy-anion (CO3) along with the clockwise rotation. In addition to that, reduction of c-axis is one of the key factors to be noticed such that better conformation of the phase transition from Calcite-I to Calcite-II could be evidenced. This conformation can be explained on the basis of the (104) peak diffraction intensity with respect to the number of shock pulses. As per the crystallographic structure of CaCO3 (a=4.991, b=4.991 and c=17.062), the c-axis is 3.4 times longer than that of a and baxes [START_REF] Simon | Structural Variations in Carbonates[END_REF][START_REF] Bridgman | The high pressure behavior of miscellaneous minerals[END_REF]. During the shock wave loaded condition, the c-axis undergoes a strong compression by the impact of shock waves and hence, oxy-anion (CO3) and cation (Ca) experience rotational effect and anti-parallel displacement from the original position along with the c-axis since the planar CO3 groups are oriented perpendicular to the c-axis. Fig. 7 clearly shows the higher angle shift and peak broadening which suggest that the disordered structure has taken place due to the occurrence of rotational effect at 50 shocks. During the antiparallel displacement of entire cation sub-lattice and oxy-anion, loss of center of symmetry has occurred so that the length of the c-axis has significantly reduced and as a result, the Calcite-II emerges at 50 shocks. The schematic diagram of the possible mechanism of shock wave induced phase transition of calcite -I-II-III is presented in Fig. 7.

J o u r n a l P r e -p r o o f

J o u r n a l P r e -p r o o f

J o u r n a l P r e -p r o o f

Calcite-II to Calcite -III phase transition

Based on the previous reports [START_REF] Simon | Structural Variations in Carbonates[END_REF][START_REF] Bridgman | The high pressure behavior of miscellaneous minerals[END_REF][START_REF] Suito | Phase relations of CaCO3 at high pressure and high temperature[END_REF], the second phase transition of calcite -II to calcite -III is somewhat elusive and the above-mentioned phase transition has occurred due to the strong displacement of cations and oxy-anion rotation caused by the impact of shock waves.

At this phase transition, the length of the c-axis is significantly reduced due to the strong compression of the c axis of calcite-II. Hence, there is a large volume change taking place during this phase transition due to the discontinuity of anions and cations. Moreover, the structure of calcite -III has two consecutive planes containing the c axis wherein carbonate ions are J o u r n a l P r e -p r o o f positioned at the planes mid-way between the layers of Ca ions [START_REF] Pippinger | Puzzling calcite-III dimorphism: crystallography, high-pressure J o u r n a l P r e -p r o o f behavior, and pathway of single-crystal transitions[END_REF]. According to the literature, it is also observed two planes in the Calcite-III structures (Fig. 7c). At 100 shocks, the test sample has experienced high transient pressure on the structures which are due to the instability of the crystal structures so that the calcite-II is phase transformed to calcite-III. At this stage, there is a strong displacement of cations and almost 90-degree rotation of oxy-anions takes place. In Fig. 7c, the schematic diagram clearly shows the displacement of calcium cites (green-original and red -displaced position) and rotation of oxy-anions (CO3). Due to the higher disorder of the crystallographic structures, calcite -III has lower symmetry and the observed XRD pattern also reveals the lower symmetry due to the lacking of strong and intense diffraction peaks. Note that, so far, there is no definite assessment found for calcite -III structure even though so many reports are available [START_REF] Simon | Structural Variations in Carbonates[END_REF][START_REF] Bridgman | The high pressure behavior of miscellaneous minerals[END_REF][START_REF] Davis | X-ray Diffraction Data on Two High-Pressure Phases of Calcium Carbonate[END_REF][START_REF] Guillaume | High-pressure X-ray diffraction study of carbonates: MgCO3, CaMg(CO3)2, and CaCO3[END_REF][START_REF] Suito | Phase relations of CaCO3 at high pressure and high temperature[END_REF]. However, based on the available literature, the obtained results are found to be well corroborated with the reported XRD patterns of Davis (1964) [START_REF] Davis | X-ray Diffraction Data on Two High-Pressure Phases of Calcium Carbonate[END_REF],

Guillaume Fiquet et al (1994) [START_REF] Guillaume | High-pressure X-ray diffraction study of carbonates: MgCO3, CaMg(CO3)2, and CaCO3[END_REF] and Kaichi Suito et al (2001) [START_REF] Kalaiarasi | Shock wave induced anatase to rutile TiO2 phase transition using pressure driven shock tube[END_REF].

Reversible Phase transitions of Calcite -I-II-III-II-I

As discussed in the previous sections, the calcite phase transition takes place due to the displacement of cations and rotational order-disorder of oxy-anions. In addition to that, most of the order-disorder crystallographic phase transitions can be reversible which has been well documented in several high-pressure experiments [START_REF] James | Dynamic compression and volatile release of carbonates[END_REF][START_REF] Guillaume | High-pressure X-ray diffraction study of carbonates: MgCO3, CaMg(CO3)2, and CaCO3[END_REF]. The displacive atomic positions can come back to the original position and hold the ambient phase during the decompression of pressure. In the case of calcite, Guillaume Fiquet et al have demonstrated the Calcite-I-III-I switchable phase transition at 4.1 GPa. Moreover, this type of phase transition is very usual at static high-pressure compression and decompression process [START_REF] Guillaume | High-pressure X-ray diffraction study of carbonates: MgCO3, CaMg(CO3)2, and CaCO3[END_REF]. Remarkably in the present experiment, it is observed an array type switchable phase transition occurring between three crystallographic structures (calcite -I-II-III-II-I) at dynamic shock wave loaded conditions. To the best of our knowledge, this is the first observation made on switchable phase transition occurring between three crystallographic phases influenced by shock waves. The reason behind the switchable phase transition of calcite, at a higher number of shock wave loaded conditions, is that the oxy-anions and cations do not undergo further disorder process (calcite-IV and V) and it may be due to the dynamic physical effect of re-crystallization [START_REF] Sivakumar | Switchable Phase Transformation (Orthorhombic -Hexagonal) of Potassium Sulfate Single Crystal at Ambient Temperature by Shock Waves[END_REF].

J o u r n a l P r e -p r o o f However, calcite-III tries to re-orient along with the crystallographic c-axis at a higher number of shocks loaded conditions. While the number of shock pulses is increased the reorientation angle is changed so that the forward phase transition occurs with the sequence of calcite-I-II-III. Fig. 8a exhibits the rotation and displacement of oxy-anion as well as cation such that Fig. 8b shows the crystallographic structural shape along the view of the c-axis. Such kind of materials capable of performing an array of switchable phase transitions can be used in the environment-monitoring sensors, pressure transmitters, molecular switches, and resistive memories [START_REF] Yuan | Mayanovic; Application of calcite, Mg-calcite, and dolomite as Raman pressure sensors for high-pressure, high-temperature studies[END_REF][START_REF] Haaring | Sudholter Electrochemically Assisted Deposition of Calcite for Application in Surfactant Adsorption Studies[END_REF]. NPs. In the present observation, FTIR measurement has been performed over the wavenumber region of 4000-400cm -1 using a Perkin Elmer FTIR spectrometer and the observed FTIR spectra of the control and shocked CaCO3 NPs are displayed in Fig. 9. Based on the literature, carbonate molecule has four normal modes of vibration peaks i.e. In-plane bending mode ( ), Out-ofplane bending mode ), Asymmetric stretching vibration carbonate ( ), and Symmetric stretch of carbonate ( ). As seen in Fig. 9, a few FTIR bands are found as that of 708, 872, 1437 and 1801 cm -1 such that all the observed band positions are found to be well-matched with the characteristic bands of CaCO3 [START_REF] Abdolmohammadi | Enhancement of J o u r n a l P r e -p r o o f Mechanical and Thermal Properties of Polycaprolactone/Chitosan Blend by Calcium Carbonate Nanoparticles[END_REF]. Such kind of array of switchable phase transitions offer a new possibility for the making of devices such as environment-monitoring sensors, pressure transmitters, molecular switches, and resistive memories along with the scope to design new multifunctional materials so that the calcite NPs are strongly suggested to be a potential candidate for the above-mentioned applications.

Compliance with ethical standards

None

Fig. 1

 1 Fig.1 Powder XRD pattern of the calcinated CaCO3 NPs with the simulated Calcite-I

Fig. 2

 2 Fig.2 Powder XRD patterns of the control and shocked CaCO3 NPs -Calcite phases

Fig. 3 Fig. 5 . 10 Fig. 4

 35104 Fig.3 Zoomed-in version of crystalline peaks for the control and shocked calcite [a] (104) and [b] simulated pattern of Calcite I, II and III

Fig. 5

 5 Fig.5 Shocked-phase profile of calcite with respect to the number of shock pulses

Fig. 7

 7 Fig.7 Possible mechanism of shock wave induced phase transition from calcite -I-II-III (a) calcite -I (b) calcite -II and (c) calcite -III (small blue ball and big red balldisplaced positions)

Fig. 8

 8 Fig.8 Schematic diagram of phase transition of calcite (a) Rotation and displacement of oxyanion and cation (b) Calcite crystallographic structure along the view of c-axis

Fig. 9 FTIR

 9 Fig.9 FTIR spectra of the control and shocked CaCo3 NPs

Acknowledgement

The authors thank Department of Science and Technology (DST), India for DST-FIST progarmme (SR/FST/College-2017/130 (c)). The project was supported by Researchers Supporting Project number (RSP-2021/231), King Saud University, Riyadh, Saudi Arabia.

J o u r n a l P r e -p r o o f

Conflict of interest

The authors declare that they have no conflict of interest.

Conflict of interest

The authors declare that they have no conflict of interest.

J o u r n a l P r e -p r o o f


Azim Roussanaly

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Asif Ahmed

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The aim of this document is to describe the metadata about videos or contents provided by local channels producers. In fact, the collaborators opted for adopting the Dublin Core Standard [START_REF] Stuart | Dublin core metadata for resource discovery[END_REF] to present knowledge about metadata. Dublin Core was firstly presented in 1995 and is considered as a vocabulary of fifteen properties aiming to present a wide range of resources [START_REF] Stuart | The dublin core metadata initiative[END_REF].

The fifteen element Dublin Core described in this standard is part of a larger set of metadata vocabularies and technical specifications maintained by the Dublin Core Metadata Initiative (DCMI). The DCMI presents two broad classes of qualifiers [START_REF] Stuart | The dublin core metadata initiative[END_REF] :

-Element Refinements : A refined element shares the meaning of the unqualified element, but with a more restricted scope. -Encoding Schemes : Schemes help to identify the interpretation of an element value (type format, standard, etc.). The approved qualifiers do not constitute a closed set. It is expected that implementers will develop additional qualifiers for use within local applications or specific domains. The table 1 presents the basic Dublin Core Metadata Element Set defined by DCMI :

Detailed Description of Videos Metadata

Basing on the Dublin Core Metadata Element Set and focusing on our Studying case, the collaborators have provided a similar set of qualifiers that aim to present the Knowledge about the videos used for SmartVideo project. The SmartVideo Metadata Element have provided additional needed elements beside removing some unneeded elements or refinements.

The table 2

Diving Deeper into the Elements Values

We notice that several fields are defined using an Identifiant having an URI format and a Title field containing the important data. So, we are going to explore only the Title field of each element. After a thorough analysis, some refinement values are more defined below :

• Creator.

Introduction to OAI-PMH

The Open Archives Initiative Protocol for Metadata Harvesting (OAI-PMH) provides an application-independent interoperability framework based on meta-data harvesting [START_REF] Carl | The open archives initiative protocol for metadata harvesting[END_REF]. OAI-PMH is a service giving a simple technical option for data providers to make their metadata available to services.

There are two classes of participants in the OAI-PMH framework :

• Data Providers : administer systems that support the OAI-PMH as a mean of exposing metadata • Service Providers : use metadata harvested via the OAI-PMH as a basis for building value-added services The OAI-PMH most related keywords are : • Harvester : A harvester is a client application that issues OAI-PMH requests. • Repository : A repository is managed by a data provider to expose metadata to harvesters. • Item : An item is a constituent of a repository from which metadata about a resource can be disseminated. • Unique Identifier : A unique identifier unambiguously identifies an item and is used for extracting metadata from the item. • Record : A record is metadata from a given item expressed in a single format. • Set : A set is an optional construct for grouping items for the purpose of selective harvesting. • Selective Harvesting : Selective harvesting allows harvesters to limit harvest requests to portions of the metadata.

OAI-PMH API Requests

OAI-PMH requests are expressed as HTTP requests. Requests must be submitted using either the HTTP GET or POST methods. POST has the advantage of imposing no limitations on the length of parameters. Repositories must support both GET and POST methods. There is a single base URL for all requests. In addition to the base URL, all requests consist of a list of keyword parameters, which take the form of key=value pairs.

• key : String Verb • value : One of the defined OAI-PMH requests -GetRecord : Retrieve an individual metadata record for a given item.

-Identify : Retrieve information about a repository.

-ListIdentifiers : Abbreviated form of ListRecords, retrieving only headers than records.

-ListMetadataFormats : Retrieve the metadata formats available from a repository. -ListRecords : Harvest records from a repository and return all metadata. -ListSets : Retrieve the set structure, useful for selective harvesting. The OAI-PMH API developed for SmartVideo Grand Est project contains the corresponding endpoints :

• data by publisher or channel The listing 1 shows an example of using the OAI-PMH API to recuperate metadata of a given video (ID = "NrQvNcBkzg").

Listing 1 -Get Record for a given video { " results ": "1" , " cursor ": 0 , " title ": " s a n t " } ] , " dc : description ": " La Ville d ' Epinal lance une nouvelle campagne de d p i s t a g e massif dans d i f f r e n t s quartiers de la commune pour toucher ceux qui n ' oseraient pas f o r c m e n t se rendre en pharmacie , chez leur m d e c i n ou dans un laboratoire ." , " dc : publisher ": [ { " identifier ": " ME0000019 " , " title ": " VosgesTV " }

TABLE 2 -

 2 SmartVideo Metadata Element Set

	details for more the elements (properties) utilized for describing
	the videos.

  Title : 37 Authors, Once per video e.g. Karim Dridi, Anthony Sap, Lucie Perrin, etc. • Subject.Title : 3528 keyword, Multiple per video e.g. boulangerie, centre-commercial, champignons, chanteur, indien, industrie, innovation, uisine, Culture, Divertissement, Economie, Education / Formation, Environnement, Faits divers, Information, Politique, Santé, Société, Sport, Territoire / Patrimoine, Tradition, etc.

• Publisher.Title : 4 Channels, Once per video e.g. Alsace 20, Canal 32, Moselle TV, Vosges TV. • Contributor.Title : 47 Producers, Once per video e.g. ANA films, ARGANE PRODUCTIONS, Alpaga Films, Alsace 20, Anoki, Blokk, CV Production, Canal 32, Dora Films, French Connection, Hibou Production, Holden, Hutong productions, Iskra, etc. • Type.Title : 8 Genres, Once per video e.g. Bande annonce, Captation culturelle, Captation sportive, Documentaire, Fiction, Magazine/Emission, Programme court, Reportage. • Source.Title : 34 Source of the provided videos, Once per video e.g. A feu doux, Le journal de VosgesTV, La case Doc, Sports week-end, Entre nous, Quon se le dise, Concert / Spectacle vivant, Météo, Bandeannonce, Place publique, etc. • RightsHolders.Title : 40 Rights Holders, Once per video e.g. Lyon Capitale TV, Machette prouction, Mara Films, Octobre Production, Opéra national de Lorraine, Oxymore, P6 Productions, Pylprod, Real production, TS production, The Kingdom, Tryptique films, etc.

  /noozy.fr/oai?set=genre : Selective harvesting, return metadata by type or genre • http://noozy.fr/oai?set=theme : Selective harvesting, return metadata by subject or thematic • http://noozy.fr/oai?set=chaine : Selective harvesting, return meta-

	http://noozy.fr/oai?verb=ListIdentifiers : Get all video identifiers
	(headers)
	• http://noozy.fr/oai?verb=ListIdentifiers&from=2021-01-29 : Get all
	video identifiers from 29 January 2021
	• http ://noozy.fr/oai ?verb=ListIdentifiers&from=2021-01-29%2000 :00 :00 :
	Get all video identifiers from 29 January 2021 specifying the time zone
	• http://noozy.fr/oai?verb=ListIdentifiers&from=2021-01-29&until=
	2021-02-29 : Get all identifiers from 29 January to 29 February 2021
	• http://noozy.fr/oai?verb=ListRecords : Get all metadata about items
	(with pagination limit = 10)
	• http://noozy.fr/oai?verb=ListRecords&page=1 : Get records of the se-
	cond page
	• http://noozy.fr/oai?resumptionToken=eyJ2ZXJiIjoiTGlzdFJlY29yZHM
	iLCJwYWdlIjoxfQ== : Using resumption token to automatically go to the
	next page
	• http://noozy.fr/oai?verb=GetRecord&identifier=NrQvNcBkzg : Return
	all metadata about a video given its ID
	• http://noozy.fr/oai?set=emi : Selective harvesting, return metadata by
	emission or program (pagination limit = 20)
	• http:/

" request ": " verb = GetRecord \& identifier = NrQvNcBkzg " , 5 " responseDate ": "2021 -06 -15 T20 :56:10+02:00" , " GetRecord ": [ { " header ": { " identifier ": " NrQvNcBkzg " , 10 " datestamp ": "2021 -01 -26" } , " metas ": { " dc : title ": " Nouvelle campagne " , " dc : identifier ": " NrQvNcBkzg " ,

15

" dc : subject ": [ { " identifier ": " TH0010 " , " title ": " S a n t " } , 20 { " identifier ": " TAG005880 " , " title ": " D p i s t a g e Covid -19" } , { 25 " identifier ": " TAG004928 " , " title ": " Covid -19" } , { " identifier ": " TAG000274 " , ] ,

40 " dc : created ": "2021 -01 -26 T09 :30:55+01:00" , " dc : modified ": "2021 -01 -26 T09 :31:11+01:00" , " dc : available ": "2021 -01 -21 T00 :00:00+01:00" , " dc : type ": [ {

45

" identifier ": " ME0000007 " , " title ": " Reportage " } ] , " dc : extent ": "00:02:30" , 50 " dc : source ": { " identifier ": " EMI000197 " , " title ": " Le journal de VosgesTV " } , " dc : coverage ": [

55

{

" lat ": 48.17006 , " lng ": 6.484474 } ] , 60 " dc : licence ": " free " , " dc : rightsHolder ": [ { " identifier ": " ME0000026 " , " title ": " VosgesTV "

65 } ] , " dc : audience ": " departement " } } 70 ] }

Conclusion

The SmartVideo Metadata Element Set is elaborated basing on the Dublin Core Standard that is considered as the best standard to describe thoroughly all the needed fields aiming to present completely a video.