Hydrothermal/Solvothermal Crystal Growth: an Old but Adaptable Process

Abstract

Hydrothermal crystal growth can be described as a low temperature process under pressure using an aqueous solution as the solvent. The temperature gradient controls the transport phenomenon from the nutrient to the seeds. The solvothermal term is generally used when the solvent is a non‐aqueous solution. Different aspects will be particularly discussed: (a) The principle of hydrothermal/solvothermal crystal growth processes. (b) A brief history of the development of such processes. (c) The main factors involved during the crystal growth and their impact on the quality of the resulting macroscopic single crystals. (d) How these physical and chemical factors can be optimized to improve the quality of the crystals. The conclusions focus on the future developments of hydrothermal or solvothermal crystal growth processes.

View point on hydrothermal sintering: Main features, today's recent advances and tomorrow's promises

“…6.d). Finally, a parallel can be made between hydrothermal crystal growth [42] and hydrothermal sintering of -quartz [41] where the driving force is the temperature gradient and the local pressure gradient, respectively. In both cases, the alkaline medium strongly favors the dissolution step by increasing the rate of dissolution.…”

Metal Phosphides and Phosphates‐based Electrodes for Electrochemical Supercapacitors

“…Hydrothermal/solvothermal Method: For transition metal phosphates, the general procedure of "hydrothermal/solvothermal" is to perform the designed chemical reactions in selected solvents in sealed vessels. [111,112] For instance, various types of cobalt phosphates (e.g., CoHPO 4 ·3H 2 O, [48] Co 11 (HPO 3 ) 8 (OH) 6 , [113] and Co 3 (PO 4 ) 2 [114,115] ), nickel phosphates (e.g., Ni 11 (HPO 3 ) 8 (OH) 6 , [116] VSB-5, [117,118] and Ni 2 P 2 O 7 [119] ), manganese phosphates (e.g., Mn 3 (PO 4 ) 2 [108,120] and MnPO 4 ·H 2 O [121] ), vanadyl phosphates (e.g., VOPO 4 ·2H 2 O, [122] ) and silver phosphates (e.g., Ag 3 PO 4 [123] ) have been reported. The hydrothermal/solvothermal processes have also been adopted to prepare bimetallic phosphate, such as Co-Ni pyrophosphates, [124] which have shown improved performances compared to the monometallic phosphates.…”

“…Hydrothermal/solvothermal Method : For transition metal phosphates, the general procedure of “hydrothermal/solvothermal” is to perform the designed chemical reactions in selected solvents in sealed vessels . For instance, various types of cobalt phosphates (e.g., CoHPO 4 ·3H 2 O, Co 11 (HPO 3 ) 8 (OH) 6 , and Co 3 (PO 4 ) 2 ), nickel phosphates (e.g., Ni 11 (HPO 3 ) 8 (OH) 6 , VSB‐5, and Ni 2 P 2 O 7 ), manganese phosphates (e.g., Mn 3 (PO 4 ) 2 and MnPO 4 ·H 2 O), vanadyl phosphates (e.g., VOPO 4 ·2H 2 O,) and silver phosphates (e.g., Ag 3 PO 4 ) have been reported.…”

Role of the Sulphur Source in the Solvothermal Synthesis of Ag-CdS Photocatalysts: Effects on the Structure and Photoactivity for Hydrogen Production

“…Most of the published works found the direct relationship between the crystallinity and photoactivity in the CdS nanostructures [34,35]. However, in recent studies we have demonstrated [29,30] the best photoactivity results for CdS nanostructures obtained at low solvothermal temperatures, associated with the formation of small crystalline CdS structures with quantum confinement effect (QD).…”

“…Among the different existing methodologies of nanosynthesis [25][26][27][28], we have studied in detail the solvothermal method because it is a simple one-pot process performed at low temperature that allows the preparation of well-crystallized materials. This methodology allows the control of the physicochemical properties and nanmorphology through the modification of the syntheses parameters described by Demazeau et al [29]. Solvothermal synthesis is a versatile methodology that has been succesfully applied for the obtention of oxides, nitrides, phosphides and even heterostructures for different photocatalytic applications [30][31][32][33].…”