TY - JOUR

T1 - Phase evolution from volborthite, cu3(V2o7)(oh)2∙2h2o, upon heat treatment

AU - Ismagilova, Rezeda M.

AU - Zhitova, Elena S.

AU - Krivovichev, Sergey V.

AU - Sergeeva, Anastasia V.

AU - Nuzhdaev, Anton A.

AU - Anikin, Leonid P.

AU - Krzhizhanovskaya, Mariya G.

AU - Nazarova, Maria A.

AU - Kupchinenko, Anastasia N.

AU - Zolotarev, Andrey A.

AU - Kutyrev, Anton V.

AU - Bukhanova, Daria S.

AU - Kuznetsov, Ruslan A.

AU - Khanin, Dmitry A.

N1 - Publisher Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

PY - 2021/12

Y1 - 2021/12

N2 - In the experiments on volborthite in situ and ex situ heating, analogues of all known natural anhydrous copper vanadates have been obtained: ziesite, pseudolyonsite, mcbirneyite, fingerite, stoiberite and blossite, with the exception of borisenkoite, which requires the presence of As in the V site. The evolution of Cu‐V minerals during in situ heating is as follows: volborthite Cu3(V2O7)(OH)2∙2H2O (30–230 °C) → X‐ray amorphous phase (230–290 °C )→ ziesite β‐Cu2(V2O7) (290–430 °C) → ziesite + pseudolyonsite α‐Cu3(VO4)2 + mcbirneyite β‐Cu3(VO4)2 (430–510 °C) → mcbirneyite (510–750 °C). This trend of mineral evolution agrees with the thermal analytical data. These phases also dominate in all experiments with an ex situ annealing. However, the phase compositions of the samples annealed ex situ are more complex: fingerite Cu11(VO4)6O2 occurs in the samples annealed at ~ 250 and ~ 480 °C and quickly or slowly cooled to room temperature, and in the sample annealed at ~ 850 °C with fast cooling. At the same time, blossite and stoiberite have been found in the samples annealed at ~ 480–780 and ~ 780–850 °C, respectively, and slowly cooled to room temperature. There is a trend of decreasing crystal structure complexity in the raw phases obtained by the in situ heating with the increasing temperature: volborthite → ziesite → mcbirneyite (except of pseudolyonsite). Another tendency is that the longer the sample is cooled, the more complex the crystal structure that is formed, with the exception of blossite, most probably because blossite and ziesite are polymorphs with identical crystal structure complexities. The high complexity of fingerite and stoiberite, as well as their distinction by Cu:V ratio, may explain the uncertain conditions of their formation.

AB - In the experiments on volborthite in situ and ex situ heating, analogues of all known natural anhydrous copper vanadates have been obtained: ziesite, pseudolyonsite, mcbirneyite, fingerite, stoiberite and blossite, with the exception of borisenkoite, which requires the presence of As in the V site. The evolution of Cu‐V minerals during in situ heating is as follows: volborthite Cu3(V2O7)(OH)2∙2H2O (30–230 °C) → X‐ray amorphous phase (230–290 °C )→ ziesite β‐Cu2(V2O7) (290–430 °C) → ziesite + pseudolyonsite α‐Cu3(VO4)2 + mcbirneyite β‐Cu3(VO4)2 (430–510 °C) → mcbirneyite (510–750 °C). This trend of mineral evolution agrees with the thermal analytical data. These phases also dominate in all experiments with an ex situ annealing. However, the phase compositions of the samples annealed ex situ are more complex: fingerite Cu11(VO4)6O2 occurs in the samples annealed at ~ 250 and ~ 480 °C and quickly or slowly cooled to room temperature, and in the sample annealed at ~ 850 °C with fast cooling. At the same time, blossite and stoiberite have been found in the samples annealed at ~ 480–780 and ~ 780–850 °C, respectively, and slowly cooled to room temperature. There is a trend of decreasing crystal structure complexity in the raw phases obtained by the in situ heating with the increasing temperature: volborthite → ziesite → mcbirneyite (except of pseudolyonsite). Another tendency is that the longer the sample is cooled, the more complex the crystal structure that is formed, with the exception of blossite, most probably because blossite and ziesite are polymorphs with identical crystal structure complexities. The high complexity of fingerite and stoiberite, as well as their distinction by Cu:V ratio, may explain the uncertain conditions of their formation.

KW - Blossite

KW - Copper vanadate

KW - Fingerite

KW - High temperature

KW - Mcbirneyite

KW - Pseudolyonsite

KW - Stoiberite

KW - Thermal analysis

KW - Volborthite

KW - Ziesite

UR - http://www.scopus.com/inward/record.url?scp=85119682635&partnerID=8YFLogxK

U2 - 10.3390/min11121312

DO - 10.3390/min11121312

M3 - Article

AN - SCOPUS:85119682635

VL - 11

JO - Minerals

JF - Minerals

SN - 2075-163X

IS - 12

M1 - 1312

ER -