مطالعه تاثیر افزودن بیسموت قبل و بعد از کلسیناسیون بر خواص الکتریکی پیزوسرامیک‌های (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3
محورهای موضوعی : سرامیک ها و مواد نسوز
راضیه حیاتی
1
(گروه مهندسی مواد، دانشکده مهندسی، دانشگاه یاسوج، یاسوج، ایران)
محمد علی بهره ور
2
(پژوهشکده نیمه هادی، پژوهشگاه مواد و انرژی، کرج)
کلید واژه: خواص الکتریکی, Bi2O3, پیزوسرامیک بدون سرب, BCZT, زینتر,
چکیده مقاله :
ترکیب پیزوالکتریک عاری از سرب Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT) با استفاده از روش متداول سرامیک‌ها سنتز و اثر افزودن 1/0% مولی Bi2O3 بر فرایند زینتر و خواص دی الکتریک، فروالکتریک و پیزوالکتریک این ترکیب مطالعه شد. در راستای کاهش اتلاف بیسموت در دماهای بالای کلسیناسیون و زینتر BCZT، ، دو روش متفاوت برای افزودن بیسموت به ساختار این ترکیب بکار گرفته شد؛ در روش اول، Bi2O3 مطابق فرمولاسیون ([(Ba0.85,Ca0.15)1-xBi3x/2](Zr0.1,Ti0.9)O3 با جبران بار در مکان‌های A-ی ساختار با سایر مواد اولیه مخلوط گردید و در روش دوم، ابتدا ترکیب BCZT سنتز و سپس Bi2O3 بدون جبران بار با این ترکیب مخلوط شد و پس از شکل دهی، سرامیک‌های BCZT-Bi زینتر گردیدند. آنالیزهای فازی و ریزساختاری با استفاده از تکنیک پراش اشعه‌‌ی X (XRD) و میکروسکوپ الکترونی روبشی (SEM) انجام گردید. نمودارهای وابستگی دمایی و فرکانسی خواص دی الکتریک، بیانگر آن بود که با اضافه کردن 1/0% مولی Bi2O3 این سرامیک‌ها از رفتار طبیعی مواد فروالکتریک تبعیت می کنند. نتایج به دست آمده حاکی از آن بود که اضافه کردن بیسموت بعد از سنتز BCZT نسبت به روش دوم در افزایش چگالی و بهبود خواص الکتریکی موثرتر می‌باشد. در دمای زینتر °C1350 برای ترکیب BCZT-Bi0.1 ضرایب پیزوالکتریک مستقیم و معکوس، فاکتور جفت‌شدگی الکترومکانیکی و قطبش باقی مانده به ترتیب d33=325 pC/m، d33*=675 pm/V، kp=0.42 و Pr=10.4 µC/cm2 به دست آمد.
Lead-free Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT) compounds were synthesized using the conventional solid state ceramic processing and the effects of Bi2O3 addition on density and electrical properties was investigated. In order to decrease the loss of Bi at high processing temperatures of BCZT, two methods were employed to introduce bismuth oxide; one, in which Bi2O3 was mixed with the raw materials and the composition was balanced for A-site substitution before calcination and the other where Bi2O3 (0.1mol%) was added after calcination, milled, compacted, and sintered (1350-1500 °C) with no compensation at A or B-sites. Phase and microstructure analyses were carried out using x-ray diffractometry and scanning electron microscopy. The temperature and frequency dependence of dielectric properties showed a normal ferroelectric behavior. Our results revealed that Bi incorporation based on the second method was more effective in increasing the density and improving the electrical properties. The highest direct and converse piezoelectric constants, planar coupling factor, and remnant polarization obtained were d33=325 pC/m, d33*=675 pm/V (d33*/d33=2.1), kp=0.42, and Pr=10.4 µC/cm2, respectively, for the BCZT sample with 0.1 mol% Bi2O3, as sintering aid, sintered at 1350 °C, which were attributed to the larger grains and higher density of the corresponding composition.
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