Synthesis of light‐coloured nanoparticles of wide band gap p‐type semiconductors CuGaO₂ and LaOCuS by low temperature hydro/solvothermal processes

Abstract

International audienceWe report here two original low temperature routes for the synthesis of nanostructured particles of p-type TCO's CuGaO2 and LaOCuS. Light grey CuGaO2 nanolayered particles (∼300 nm large and 5 nm thick) were prepared from a hydrothermal synthetic route using soluble hydrated metal nitrates as precursors and ethylene glycol (EG) as reducing agent. We found then that the initial pH of the precursor's solution is a key parameter to tune the particle sizes (from 2 µm to 300 nm) and subsequently the colour (from dark brown to light grey) of the CuGaO2 powder. LaOCuS was obtained for the first time as greyish nanolayered particles (∼100 nm large and 10 nm thick) via a solvothermal route in ethylene diamine with hydrate chloride lanthanum, copper mono oxide and elemental sulphur as precursors. We found that the control of the chloride lanthanum precursor hydration rate is of prime importance to achieve pure material and to tune the colour of the LaOCuS sample. Both CuGaO2 and LaOCuS nanolayered particles synthesized via these soft chemistry routes exhibit all the characteristics of transparent p-type semiconductor

A Review on Cu<SUB>2</SUB>O and Cu<SUP>I</SUP>-Based <I>p</I>-Type Semiconducting Transparent Oxide Materials: Promising Candidates for New Generation Oxide Based Electronics

“…5 Therefore, these types of layered-structured p-TCOs are inherently providing the anisotropic environment to the charge carriers and phonons to have suppressed scattering, and hence better thermoelectric properties. 281 282 Apart from photovoltaic, transparent electronic, vacuum microelectronic and thermoelectric related applications, Cu I -based p-types oxides are reported to have some very interesting and diverse properties and applications in magnetic, catalytic, photocatalytic, photoelectrochemical, gas sensing, superconducting, hydrogen generation and self-cleaning [283][284][285][286][287][288][289][290][291][292][293][294][295][296][297][298][299][300][301] properties. Therefore, it will not be an exaggeration to say that next decade will see the renaissance of Cu I -based p-type oxides and p-TCOs for various novel technological applications.…”

Transparent Conducting Oxides—An Up-To-Date Overview

“…As further metal, A, iron [143,144,145], cobalt [138] or chrome [146,147,148,149,150] (without doping hardly transparent) may be used as well as elements of the 2nd group of the periodic table of the elements—strontium [151,152,153,154], barium [155]—or the 3rd group—aluminum [149,156,157,158,159,160,161,162,163,164,165,166,167,168,169], gallium [168,169], indium [170], scandium [171,172], yttrium [173,174,175,176], lanthanum [175,176]. Moreover, other lanthanides such as praseodymium, neodymium samarium and europium have been applied [175,176,177], in order to get ternary semiconductor compounds.…”

“…Copper may be replaced by silver [ 136 , 137 , 138 , 139 , 140 , 141 ], palladium [ 139 ] or platinum [ 142 ]. As further metal, A, iron [ 143 , 144 , 145 ], cobalt [ 138 ] or chrome [ 146 , 147 , 148 , 149 , 150 ] (without doping hardly transparent) may be used as well as elements of the 2nd group of the periodic table of the elements—strontium [ 151 , 152 , 153 , 154 ], barium [ 155 ]—or the 3rd group—aluminum [ 149 , 156 , 157 , 158 , 159 , 160 , 161 , 162 , 163 , 164 , 165 , 166 , 167 , 168 , 169 ], gallium [ 168 , 169 ], indium [ 170 ], scandium [ 171 , 172 ], yttrium [ 173 , 174 , 175 , 176 ], lanthanum [ 175 , 176 ]. Moreover, other lanthanides such as praseodymium...…”

“…Delafossites have been grown from a melt by a slow cooling-method in air [ 166 , 183 ]. They were deposited using low temperature hydro/solvothermal processes [ 159 , 168 , 184 ], the sol-gel technology [ 146 , 147 , 149 , 153 , 185 ] and the spray pyrolysis technique [ 148 , 158 ]. Moreover, advanced methods such as (direct current (DC), radio frequency (RF)) magnetron sputtering of prefabricated targets [ 143 , 144 , 156 , 157 , 162 , 164 , 167 , 173 , 181 , 186 ], with varying temperature, pressure, oxygen flow or sputter energies [ 144 , 161 , 165 ], pulsed laser deposition [ 136 , 152 , 163 , 169 , 187 , 188 ], with varying temperature and pressure [ 187 ], thermal evaporation [ 174 ], e-beam evaporation technique [ 154 ], and (low-pressure (LP), metal-organic (MO)) chemical vapor deposition (CVD) [ 150 ] were applied.…”

Sub-micron-sized delafossite CuCrO2 with different morphologies synthesized by nitrate–citric acid sol–gel route

“…Soft-chemistry routes like hydrothermal and sol-gel are used in particular to synthesize delafossite CuCrO 2 nanopowders. Hydrothermal/solvothermal syntheses of copper and silver delafossite oxides leading to micron, sub-micron and nano-sized powders are comparatively well studied by different groups [28][29][30][31]. Sol-gel synthesis in general has advantages with respect to obtaining the metastable materials with purity and compositional homogeneity at moderate temperatures in comparison with the high-temperature ceramic route.…”