本文選題：非充滿型鎢青銅　切入點(diǎn)：鐵電相變　出處：《浙江大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：(SrxBa1-x)Nb2O6陶瓷作為非充滿型鎢青銅結(jié)構(gòu)的典型代表,由于優(yōu)異的鐵電、壓電、熱釋電以及非線性光學(xué)性能,一直受到廣泛關(guān)注。但對(duì)其介電性能、尤其是鐵電相變與低溫介電弛豫的認(rèn)識(shí)仍有待加深。基于對(duì)充滿型鎢青銅陶瓷的最新研究,本文結(jié)合其結(jié)構(gòu)演化,對(duì)(SrxBa1-x)Nb2O6陶瓷的介電性能、鐵電相變進(jìn)行了深入研究。(SrxBa1-x)Nb2O6的介電和鐵電性能隨著x而變化,其中A1/A2離子占位作為主要因素決定著變化的趨勢(shì)。當(dāng)Sr/Ba摩爾比接近1：4比值(此時(shí),離子半徑較大的Ba離子占據(jù)4個(gè)A2位,離子半徑相對(duì)小的Sr離子占據(jù)1個(gè)A1位,另一個(gè)A1位空缺),(SrxBa1-x)Nb2O6將呈現(xiàn)正常鐵電體特性,在tanδ-T圖中只出現(xiàn)一個(gè)介電異常(x=0.25)。而當(dāng)Sr/Ba摩爾比遠(yuǎn)離1：4比值時(shí),(SrxBa1-x)Nb2O6將呈現(xiàn)典型的弛豫鐵電特性,在tenδ-T圖中出現(xiàn)三個(gè)介電異常(x=0.75)。其中,非公度氧八面體傾斜和A位離子的無(wú)序分布是其出現(xiàn)弛豫鐵電性和低溫介電弛豫的結(jié)構(gòu)起源。(SrxBa1-x)Nb2O6陶瓷的鐵電疇結(jié)構(gòu)進(jìn)一步證實(shí)了其隨著x增加從正常鐵電體到弛豫鐵電體的演化。較低電場(chǎng)下的電滯回線(P-E)隨溫度的變化顯示,最大極化值(Pmax)和剩余極化值(Pr)在低溫下出現(xiàn)下降甚至幾乎為零,電滯回線出現(xiàn)線性響應(yīng)。這一現(xiàn)象的出現(xiàn)主要是因?yàn)榈蜏叵鲁C頑場(chǎng)的增加,而非再入弛豫。當(dāng)電場(chǎng)增加到足夠高時(shí),所有組分在低溫下都得到飽和的非線性電滯回線。
[Abstract]:As a typical representative of non-filled tungsten bronze structure, SrxBa1-xNb2O6 ceramics have been widely concerned because of their excellent ferroelectric, piezoelectric, pyroelectric and nonlinear optical properties. In particular, the understanding of ferroelectric phase transition and low-temperature dielectric relaxation still needs to be deepened. Based on the latest research on the filled tungsten bronze ceramics, the dielectric properties of SrxBa1-xNb2O6 ceramics have been studied in this paper in combination with their structural evolution. The dielectric and ferroelectric properties of SrxBa1-xNb2O6 vary with x, in which A 1 / A2 ion occupation is the main factor determining the change trend. When the molar ratio of Sr/Ba is close to 1: 4, The Ba ion with larger ion radius occupies 4 A2 sites, the Sr ion with relatively small ion radius occupies 1 A1 site, and the other Al vacancy position SrxBa1-xNb2O6 exhibits normal ferroelectric properties. There is only one dielectric anomaly in the tan 未 -T diagram, and when the Sr/Ba molar ratio is far from the ratio of 1: 4, SrxBa1-xNb2O6 will exhibit typical relaxor ferroelectric properties, and three dielectric anomalies will appear in the ten 未 -T diagram. Incommensurate oxygen octahedron tilt and disordered distribution of A-site ions are the structural origin of relaxation ferroelectrics and low-temperature dielectric relaxation. The ferroelectric domain structure of SrxBa1-xNb2O6 ceramics further confirms that the ferroelectric structure changes from normal ferroelectrics to relaxation with the increase of x. Evolution of ferroelectrics. The changes of hysteresis loop P-E) at lower electric field show that, The maximum polarization value Pmax) and the residual polarization value Pr) decreased to almost zero at low temperature, and the hysteresis loop showed a linear response, which was mainly due to the increase of coercive field at low temperature. When the electric field is high enough, the saturated nonlinear hysteresis loop is obtained at low temperature.
【學(xué)位授予單位】：浙江大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TQ174.1

【參考文獻(xiàn)】

相關(guān)碩士學(xué)位論文 前1條

1 白陽(yáng);充滿型鎢青銅鈮酸鹽陶瓷的結(jié)構(gòu)與性能[D];浙江大學(xué);2011年

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本文編號(hào)：1564645