CN107640970A - The AgNb of low frequency low-dielectric loss is co-doped with titania-based dielectric ceramic material and preparation method thereof - Google Patents

Abstract

The invention discloses a kind of AgNb of low frequency low-dielectric loss to be co-doped with titania-based dielectric ceramic material and preparation method thereof, and the formula of the ceramic material is (Ag_1/4Nb_3/4)_xTi_1‑xO₂, wherein x expression molar fractions, x value is 0.005~0.01.The preparation method of ceramic material of the present invention is simple, reproducible, high yield rate, by introducing metal element A g in the mono- titanium dioxide base ceramic materials mixed of Nb, makes ceramic material in frequency be 40~10⁶There is high-k (＞ 10 in the range of Hz⁴), low-dielectric loss (＜ 0.09), especially significantly reduce ceramic material low-frequency dielectric loss, 40~10³Dielectric loss remains at less than 0.06 in Hz frequency ranges, while has excellent frequency and temperature stability, is maintained between 10%~10%, meets the parameter request of ceramic capacitor, has huge application value.

Description

AgNb co-doped titania-based dielectric ceramic material with low frequency and low dielectric loss and its preparation preparation method

technical field

The invention belongs to the technical field of ceramic materials, and in particular relates to a titanium dioxide-based dielectric ceramic material with high dielectric constant and low dielectric loss and a preparation method thereof.

Background technique

The rapid development of the information age has brought a new situation to the electronics industry. At present, the microelectronics industry has undoubtedly become one of the largest industries in the world, and capacitors are one of the main components used in large quantities in electronic equipment. Whether it is Mobile phones, computers, home appliances, and automobiles that we use in our daily lives play a very important role in industrial instrumentation, agriculture, defense departments, and even aerospace.

Dielectric materials, as important functional materials, are widely used in many fields such as capacitors, memories, and microelectronic components. With the continuous development of manufacturing technology and the continuous reduction of the feature size of integrated circuits, the integration, miniaturization and high-speed of electronic components have become an important research topic in the field of modern information. Commonly used dielectric materials such as strontium barium titanate and lead zirconate titanate are mostly ferroelectric materials. Since ferroelectric materials undergo ferroelectric-paraelectric phase transition at the Curie temperature, the dielectric constant of ferroelectric materials varies with temperature. The change is obvious, which leads to the deterioration of the temperature stability of the device and limits its application range. For lead-based materials, since the system contains lead element, lead element is an environmentally unfriendly metal element. Therefore, it is imminent to develop a lead-free dielectric material with high dielectric constant, low dielectric loss, and good frequency and temperature stability.

TiO2-based ceramics have attracted much attention from researchers due to their relatively high dielectric constant among simple compounds. In recent years, no matter whether it is single-doped, or two-pentavalent, three-pentavalent co-doped titanium dioxide-based ceramic materials have emerged in an endless stream, but most of the materials cannot meet the requirements of high dielectric constant and low dielectric loss at the same time. Especially single-doped titania-based ceramic materials. For example, niobium-doped titania-based ceramics have a relatively high dielectric constant (>10 ⁴ ), but their low-frequency dielectric loss is relatively large (>1), which cannot meet the requirement of low dielectric loss.

Contents of the invention

The technical problem to be solved by the present invention is to provide an AgNb co-doped titanium dioxide-based dielectric with high dielectric constant, low dielectric loss (especially low dielectric loss at low frequency), good frequency temperature stability, strong practicability, and easy production. An electric ceramic material, and a preparation method for the ceramic material is provided.

The general formula of the ceramic material used to solve the above technical problems is (Ag _1/4 Nb _3/4 ) _x Ti _1-x O ₂ , where x represents the mole fraction, and the value of x is 0.005-0.01.

The preparation method of the above-mentioned AgNb co-doped titania-based dielectric ceramic material is as follows:

1. According to the stoichiometry of (Ag _1/4 Nb _3/4 ) _x Ti _1-X O ₂ , weigh the raw materials Ag ₂ O, Nb ₂ O ₅ and TiO ₂ with a purity of more than 99.5%, and mix them thoroughly by ball milling for 16~ 24 hours, drying at 80-100° C. for 12-24 hours to obtain a raw material mixture.

2. Pre-calcining the raw material mixture at 1000-1200° C. for 2-4 hours to obtain calcined powder.

3. Sintering the calcined powder at 1400-1450° C. for 5-10 hours after secondary ball milling, granulation, tableting and debinding, to obtain AgNb co-doped titanium dioxide-based dielectric ceramic material.

In the above step 2, the raw material mixture is preferably pre-calcined at 1100° C. for 3 hours.

In the above step 3, it is preferable to sinter the calcined powder at 1450° C. for 10 hours after secondary ball milling, granulation, tableting, and debinding.

The present invention introduces the metal element Ag into the Nb single-doped titanium dioxide-based ceramic material, so that the ceramic material has a high dielectric constant, and significantly reduces the low ^- frequency dielectric loss of the ceramic material. The dielectric loss within the range is always kept below 0.06, and it has excellent frequency and temperature stability, which is kept between -10% and 10Z%.

The preparation method of the ceramic material of the invention is simple, good in repeatability, high in yield, strong in practicability and easy in production.

Description of drawings

Fig. 1 is the XRD pattern of the ceramic material prepared in Examples 1-2.

Fig. 2 is a graph showing the relationship between the dielectric constant of the ceramic materials prepared in Examples 1-6 and the test frequency.

Fig. 3 is a graph showing the relationship between dielectric loss and test frequency of ceramic materials prepared in Examples 1-6.

FIG. 4 is a graph showing the relationship between the dielectric constant of the ceramic material prepared in Example 1 and the temperature stability as a function of the test temperature.

Fig. 5 is a diagram showing the relationship between the dielectric constant of the ceramic material prepared in Example 2 and the variation of the test temperature and the temperature stability.

detailed description

The present invention will be described in further detail below in conjunction with the accompanying drawings and embodiments, but the protection scope of the present invention is not limited to these embodiments.

Example 1

1. According to the stoichiometry of (Ag _1/4 Nb _3/4 ) _0.005 Ti _0.995 O ₂ , weigh the raw materials Ag ₂ O (99.7% purity) 0.0361g, Nb ₂ O ₅ (99.99% purity) 0.1237g, TiO ₂ (purity 99.5%) 19.8401g, and pack in the nylon jar, be ball milling medium with zirconium ball, dehydrated alcohol, the mass ratio of dehydrated alcohol and raw material mixture is 1:1.2, ball mills with ball mill 401 revolutions per minute After 24 hours, the zirconium balls were separated, the raw material mixture was dried at 80° C. for 24 hours, and ground with a mortar for 30 minutes to obtain a raw material mixture.

2. Put the raw material mixture in an alumina crucible, cover it, heat it up to 1100°C at a heating rate of 3°C/min and keep it warm for 3 hours, cool it down to room temperature naturally, take it out of the furnace, and grind it with a mortar for 5 minutes to obtain a calcined powder.

3. Put the calcined powder into a nylon tank, use zirconium balls as grinding balls, and absolute ethanol as the ball milling medium. The mass ratio of absolute ethanol to calcined powder is 1:1.2, mix and ball mill for 20 hours, and separate the zirconium balls , dry the calcined powder at 80°C for 24 hours, and grind it with a mortar to obtain the calcined powder of the second ball mill; then add a polyvinyl alcohol aqueous solution with a mass fraction of 5%, and the addition amount of the polyvinyl alcohol aqueous solution is 50% of the mass of the calcined powder after the secondary ball milling, granulation, passing through a 120 mesh sieve to make spherical powder, and putting the spherical powder into a stainless steel mold with a diameter of 11.5mm, using a powder tablet press at 6MPa Press it into a cylindrical blank with a thickness of 1.5mm under pressure; put the cylindrical blank on a zirconia flat plate, place the zirconia flat plate in an alumina porcelain boat, and heat up in a muffle furnace for 380 minutes to 500°C, keep warm for 2 hours, cool down to room temperature naturally with the furnace, then raise the temperature to 1000°C in a tube furnace for 100 minutes, then raise the temperature to 1450°C at a heating rate of 2°C/min, hold for 10 hours, Naturally cooled to room temperature, the AgNb co-doped titania-based dielectric ceramic material with low frequency and low dielectric loss was obtained.

Example 2

In this example _{, the} raw materials Ag ₂ O (99.7%) _0.0719g , Nb ₂ O _{5 (} 99.99%) _0.2468g , TiO ₂ (99.5%) 19.6813g, and the other steps were the same as in Example 1 to obtain an AgNb co-doped titania-based dielectric ceramic material with low frequency and low dielectric loss.

Example 3

In this example, the tube furnace is first heated to 1000°C in 100 minutes, then raised to 1410°C at a heating rate of 2°C/min, and kept for 10 hours. The other steps are the same as in Example 1 to obtain low-frequency and low-dielectric Lossy AgNb co-doped TiO2-based dielectric ceramic materials.

Example 4

In this example, in the tube furnace, the temperature is raised to 1000°C in 100 minutes, then raised to 1410°C at a rate of 2°C/min, and kept for 10 hours. Other steps are the same as in Example 2 to obtain a low-frequency low-dielectric Lossy AgNb co-doped TiO2-based dielectric ceramic materials.

Example 5

In this example, in the tube furnace, the temperature is raised to 1000°C in 100 minutes, then to 1450°C at a rate of 2°C/min, and kept for 5 hours. Other steps are the same as in Example 1 to obtain low-frequency and low-dielectric Lossy AgNb co-doped TiO2-based dielectric ceramic materials.

Example 6

In this example, the tube furnace is first heated to 1000°C in 100 minutes, then raised to 1450°C at a heating rate of 2°C/min, and kept for 5 hours. The other steps are the same as in Example 2 to obtain low-frequency and low-dielectric Lossy AgNb co-doped TiO2-based dielectric ceramic materials.

The ceramic materials prepared in the above Examples 1 and 2 were respectively subjected to XRD tests using a D/max-2200 X-ray diffractometer (manufactured by Rigaku Corporation of Japan), and the results are shown in FIG. 1 . It can be seen from Figure 1 that the ceramic materials prepared in Examples 1 and 2 are all pure perovskite-like structures without the formation of a second phase.

Polish the surface of the ceramic material prepared in Examples 1 to 6 with 320 mesh, 800 mesh, and 1500 mesh sandpaper in sequence to a thickness of 0.5 to 0.6 mm, then coat the upper and lower surfaces of the ceramic with silver paste with a thickness of 0.01 to 0.03 mm, and place it in a resistor Heat at 840°C for 30 minutes in the furnace. Agilent4294A precision impedance analyzer and E4980A LCR tester were used to test the dielectric properties of ceramics, and the results are shown in Figures 2-5. It can be seen from Figures 2 and 3 that at 1 kHz, the relative permittivity of the ceramic materials prepared in Examples 1 to 6 is 9409, 17252, 9345, 17150, 9259, 16234, and the dielectric loss is 0.036, 0.044, 0.057, 0.060 , 0.043, 0.059, and the dielectric loss in the frequency range of 40-10 ³ Hz is always kept below 0.06. It can be seen from Fig. 4 that the dielectric constant of the ceramic material prepared in Example 1 is generally concentrated at about 9000 at different frequencies in the range of -55 to 150°C, and the temperature change rate is -1.5% to 7%. It can be seen from Fig. 5 that the dielectric constant of the ceramic material prepared in Example 2 is mainly concentrated between 14000 and 16000 at different frequencies in the range of -55 to 150 °C, and the temperature change rate is -8.6% to 10%. It can be seen that the ceramic material of the present invention has high dielectric constant and low dielectric loss, and the temperature stability is always maintained between -10% and 10%, which meets the application requirements of the material.

Claims (4)

1. A low-frequency low-dielectric loss AgNb co-doped titania-based dielectric ceramic material, characterized in that: the general formula of the ceramic material is (Ag _1/4 Nb _3/4 ) _x Ti _1-x O ₂ , wherein The value of x is 0.005-0.01. 2. a kind of preparation method of the AgNb co-doped titania-based dielectric ceramic material of low frequency and low dielectric loss claimed in claim 1, is characterized in that it is made up of following steps: (1) According to the stoichiometry of (Ag _1/4 Nb _3/4 ) _x Ti _1-x O ₂ , weigh the raw materials Ag ₂ O, Nb ₂ O ₅ and TiO ₂ with a purity of more than 99.5%, and mix them thoroughly and ball mill them for 16 ~24 hours, drying at 80~100°C for 12~24 hours to obtain the raw material mixture; (2) Pre-calcining the raw material mixture at 1000-1200°C for 2-4 hours to obtain calcined powder; (3) Sinter the calcined powder at 1400-1450° C. for 5-10 hours after secondary ball milling, granulation, tableting, and debinding to obtain AgNb co-doped titanium dioxide-based dielectric ceramic materials with low frequency and low dielectric loss. 3. The method for preparing low frequency and low dielectric loss AgNb co-doped titania-based dielectric ceramic material according to claim 2, characterized in that in step (2), the raw material mixture is pre-fired at 1100° C. for 3 hours. 4. the preparation method of the AgNb co-doped titania-based dielectric ceramic material of low frequency and low dielectric loss according to claim 2 is characterized in that: in step (3), the calcined powder is subjected to secondary ball milling and granulation , Pressing, and debinding, sintering at 1450°C for 10 hours.