Abstract — β-Ga2O3 powders were synthesized by hydrothermal method at different pH values ranging from 5 to 14. Obtained powder samples, showed polycrystalline nature and monoclinic crystalline structure upon investigation through XRD. The micrographs of powder samples resulted from SEM investigations showed different morphologies ranging from basic to hierarchical structures as pH value changes. Extremely alkaline solution (with pH = 14) caused to yield hierarchical morphologies whereas the acidic solution (with pH = 5) ensued basic rod-like morphologies. Cocoon shaped morphology was maintained from neutral (pH = 7) to moderately basic (pH = 11) conditions. Optical band gaps of the samples were calculated from Kubelka-Munk plot resulted from the data obtained by UV–Visible spectroscopic analysis. Synthesized β-Ga2O3 powder samples were drop casted on glass substrate which was pre-printed with Inter Digitated Electrode pattern (IDE) of Silver (Ag) ink. These drop coated thick films are then used for the different concentrations of NH3 vapor detection at room temperature. Morphology based model proposed for room temperature NH3 sensing. It has been observed that β-Ga2O3 prepared under pH = 14 showed higher response and sensitivity due to its hierarchy in morphology and relatively lower band gap of 4.61 eV.

中文翻译：

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pH依赖形态对β-Ga2O3室温NH3传感性能的影响

摘要 — β-Ga2O3 粉体采用水热法在5~14 的不同pH 值条件下合成。得到的粉体样品经XRD 研究显示为多晶性质和单斜晶结构。由 SEM 研究得到的粉末样品的显微照片显示出不同的形态，从基本结构到分级结构，随着 pH 值的变化。极碱性溶液（pH = 14）导致产生分层形态，而酸性溶液（pH = 5）导致基本棒状形态。茧形形态从中性 (pH = 7) 到中等碱性 (pH = 11) 条件保持不变。样品的光学带隙由 Kubelka-Munk 图计算，该图由紫外-可见光谱分析获得的数据得出。合成的 β-Ga2O3 粉末样品滴铸在玻璃基板上，玻璃基板用银 (Ag) 墨水的 Inter Digitated Electrode 图案 (IDE) 预印。然后将这些滴涂厚膜用于室温下不同浓度的 NH3 蒸气检测。为室温 NH3 感测提出的基于形态的模型。已经观察到，在 pH = 14 下制备的 β-Ga2O3 由于其形态层次和相对较低的 4.61 eV 带隙而显示出更高的响应和灵敏度。