CN116178011A

CN116178011A - Novel perovskite material LaNdV 2 O 8 Is prepared by the preparation method of (2)

Info

Publication number: CN116178011A
Application number: CN202310152157.5A
Authority: CN
Inventors: 张志远; 唐莹
Original assignee: Guilin University of Technology
Current assignee: Guilin University of Technology
Priority date: 2023-02-22
Filing date: 2023-02-22
Publication date: 2023-05-30

Abstract

The invention discloses a novel microwave dielectric ceramic LaNdV ₂ O ₈ Is prepared by the preparation method of (1). (1) The lanthanum oxide, neodymium oxide and ammonium metavanadate with the purity of 99 percent are subjected to microwave dielectric ceramic LaNdV according to design ₂ O ₈ The metering ratio of (2) is formed into a weighing ingredient; (2) Ball-milling and mixing the raw materials in the step (1) in a ball-milling tank for 12 hours to obtain a mixed raw material; (3) Presintering, secondary ball milling, granulating, removing colloid, and sintering to obtain LaNdV ₂ O ₈ A material. The microwave dielectric ceramic material prepared by the method has the advantages of complex process, high purity, good chemical stability, excellent microwave dielectric property and great application prospect.

Description

Novel perovskite material LaNdV 2 O 8 Is prepared by the preparation method of (2)

Technical Field

The invention belongs to the field of inorganic materials and solid chemistry, and in particular relates to novel microwave dielectric ceramic LaNdV ₂ O ₈ Is prepared by the preparation method of (1).

Background

Microwave dielectric ceramics (Microwave dielectric ceramics, abbreviated MWDC) refers to novel functional ceramics that perform one or more functions (conduction, resonance, filtering) as a medium in a microwave frequency band circuit. Compared with the electronic components prepared from the traditional metal materials, the components such as a dielectric resonator, an amplifier, a band-pass (resistance) filter, an attenuator, an MIC dielectric substrate, a microwave substrate, a dielectric waveguide, a capacitor and the like prepared from the microwave dielectric ceramic materials have the advantages of low cost, small volume, good performance and the like. With the recent development, these electronic components play an increasing role in modern communication systems such as television broadcasting, satellite communication, communication base stations, smartphones, radars, internet of things (IOT), global Positioning System (GPS), bluetooth (Blue-tooth) technology, and Wireless Local Area Networks (WLANs).

The 5G has the advantages of low power consumption, low time delay, high speed and the like, but has higher communication frequency, and is divided into a frequency below 6GHz and a frequency above 24 GHz. Because the frequency of the 5G communication equipment is higher, the heating value and loss of the system can be increased, the stability of the system is gradually reduced, and the performance parameters (dielectric constant epsilon) of the microwave dielectric material are reduced _r Quality factor Q×f, resonant frequency temperature coefficient τ _f ) Higher demands are put forth. For microwave dielectric ceramic materials, the higher the electromagnetic frequency, the shorter the wavelength, the easier the attenuation in the medium, and the lower epsilon _r The loss is reduced, and the transmission rate of the electric signal is improved; the higher the frequency, the smaller the loss of the required material, and the higher the Q×f value is beneficial to improving the selectivity of the working frequency of the device, so the development trend of the microwave dielectric material in the future mainly comprises the following points: (1) Develop a high Q x f value and tau _f Near zero material; (2) reducing production cost; (3) deepening basic theoretical research; (4) exploring a new preparation process. To prepare a high Q×f value and τ _f Near-zero microwave dielectric ceramic, and the application provides novel microwave dielectric ceramic LaNdV ₂ O ₈ Is prepared by the preparation method of (1).

Disclosure of Invention

The invention aims to provide a novel microwave dielectric ceramic LaNdV ₂ O ₈ Is prepared by the preparation method of (1). Preparation of LaNdV ₂ O ₈ The ceramic material comprises the following specific steps:

(1) Proportioning and weighing

The raw material 15 and g is weighed according to the chemical formula of the material by a high-precision electronic balance (the precision is 0.0001 g), the raw material is calibrated and zeroed before weighing, and a sample which is easy to absorb moisture is roasted at a high temperature.

(2) One-time ball milling

The raw materials weighed according to the chemical molar ratio are put into a furnace filled with ZrO ₂ In order to ensure that the raw materials can be fully and uniformly mixed in the nylon pot of the ball, zrO with different sizes and amounts is added in the experiment ₂ Balls can be divided into three according to the size, namely 3.6 mm, 6 mm and 10.2 mmThe number ratio is 11:33:99. in view of solubility and volatility, absolute ethanol was used as a milling medium and ball milled on a planetary ball mill at a rotational speed of 170 r/min for 6 h. After the ball milling, the slurry was poured into a petri dish, dried in an oven (120 ℃) for 2 h, and finally, the powder was ground with a mortar, and then, the powder was pressed to be molded.

(3) Presintering process

The purpose of the presintering is to allow preliminary reactions between the original oxides and to obtain the desired main phase of the compound. And placing the ceramic cylinder pressed after ball milling in a muffle furnace for calcination, wherein the sintering temperature and the sintering time are also greatly different due to the different systems. Furthermore, too high or too low a burn-in temperature is detrimental to achieving optimal microwave dielectric properties.

(4) Secondary ball milling

Grinding the presintered ceramic column into powder, performing secondary ball milling according to the ball milling step in step (2), taking out the slurry after ball milling, and drying in a constant-temperature oven at 85 ℃ for later use.

(5) Granulating

And (3) putting the dried secondary ball-milling powder into a mortar, and adding PVA with the mass fraction of 5% -7% as a binder to enable the powder to be bonded into spherical particles with uniform size. Sieving the granulated powder to obtain particles with uniform particle size in the middle layer (60-mesh and 120-mesh double-layer sieving method is used in the experiment).

(6) Shaping

The granulated powder is formed by dry pressing, i.e. the powder with good fluidity and uniform granularity after granulation is put into a die with the diameter of 10 mm and pressed into a column with the height of 6.5 mm. The molding pressure was 6 MPa and the dwell time was 30 s.

(7) Discharging glue and sintering

The main purpose of the rubber discharge is to remove the binder (PVA) added during granulation, and the rubber discharge process is as follows: and (3) placing the molded ceramic sample into a muffle furnace, heating to 550 ℃ at a heating rate of 1.5 ℃/min, and preserving heat for 2 h. The purpose of sintering is to enable the grains of the sample to fully grow and improve the density of the sample. In the experiment, in order to reduce volatilization of V element, a buried firing method is adopted to sinter the sample, namely, the sample after glue discharge is placed in an alumina crucible, powder with the same components is added to cover the sample, the temperature is raised to the sintering temperature at the heating rate of 5 ℃/min, and the heat preservation time is 6 h.

(8) Polishing and hot etching of samples

In order to obtain clear microstructure morphology, it is necessary to grind and polish the sintered ceramic sample on a polishing machine, and put the polished sample into a high-temperature muffle furnace for hot corrosion. The heating rate of hot corrosion is 3 ℃/min, the hot corrosion temperature is lower than the sintering temperature of 80 ℃, and the heat preservation time is 40 min.

The microwave dielectric ceramic material prepared by the invention has complex process, but has high purity, good chemical stability and excellent microwave dielectric property.

Drawings

FIG. 1 shows a novel microwave dielectric ceramic LaNdV prepared in example 1 ₂ O ₈ Element distribution map obtained under scanning electron microscope

FIG. 2 is a conventional LaNdV prepared in example 1 ₂ O ₈ Raman mapping in raman test.

FIG. 3 shows the preparation of LaNdV in example 1 ₂ O ₈ XRD pattern of perovskite material.

Detailed Description

The following detailed description is made by way of specific examples, which are given by way of illustration of detailed embodiments and specific operation procedures on the premise of the technical scheme of the present invention, but the scope of the present invention is not limited to the following examples.

Example 1:

this example 1 design yields 15 grams of the target product LaNdV ₂ O ₈ A material. Weighing lanthanum oxide, neodymium oxide and ammonium metavanadate according to stoichiometric ratio, and then fully grinding for 6 hours in a ball milling tank to obtain mixed powder. The prepared mixed powder is processed by the detailed steps to obtain columnar blocks, the surfaces of the columnar blocks are cleaned by tweezers, and the surfaces of the columnar blocks are polished to be flat, thus obtaining the pure LaNdV ₂ O ₈ And (5) carrying out microwave testing on the block body.Fig. 1 shows a crystal morphology of the obtained product, fig. 2 shows a raman spectrum of the obtained product, and fig. 3 shows an XRD spectrum of the obtained product measured under an air atmosphere.

Claims

1. Novel microwave dielectric ceramic LaNdV ₂ O ₈ The preparation method comprises the following specific steps:

(1) Proportioning and weighing

Weighing 15 and g raw materials according to the chemical formula of the materials by a high-precision electronic balance (with the precision of 0.0001 g), calibrating and zeroing before weighing, and roasting a sample which is easy to absorb moisture at a high temperature;

(2) One-time ball milling

The raw materials weighed according to the chemical molar ratio are put into a furnace filled with ZrO ₂ In order to ensure that the raw materials can be fully and uniformly mixed in the nylon pot of the ball, zrO with different sizes and amounts is added in the experiment ₂ Balls can be divided into three types according to the size, namely 3.6 mm, 6 mm and 10.2 mm, and the number ratio is 11:33:99, a step of; taking solubility and volatility into consideration, absolute ethyl alcohol is used as a ball milling medium, and the ball milling is carried out on a planetary ball mill at a rotating speed of 170 r/min for 6 h; after ball milling, pouring the slurry into a surface dish, putting the surface dish into an incubator (120 ℃) for drying 2 h, grinding the powder by a mortar, and then compacting the powder;

(3) Presintering process

The purpose of the presintering is to allow preliminary reactions between the original oxides and to obtain the main phase of the desired compound; placing the ceramic cylinder pressed after ball milling in a muffle furnace for calcination, wherein the sintering temperature and the sintering time are also greatly different due to the different systems; in addition, too high or too low a burn-in temperature is detrimental to achieving optimal microwave dielectric properties;

(4) Secondary ball milling

Grinding the presintered ceramic column into powder, performing secondary ball milling according to the ball milling step in step (2), taking out the slurry after ball milling, and drying in a constant-temperature oven at 85 ℃ for later use;

(5) Granulating

Placing the dried secondary ball-milling powder into a mortar, and adding PVA with the mass fraction of 5% -7% as a binder to enable the powder to be bonded into spherical particles with uniform size; sieving the granulated powder to obtain particles with uniform particle size in the middle layer (the experiment uses a 60-mesh and 120-mesh double-layer sieving method);

(6) Shaping

The granulated powder is formed by dry pressing, namely, the powder with good fluidity and uniform granularity after granulation is put into a die with the diameter of 10 mm to be pressed into a column with the height of 6.5 mm; the molding pressure is 6 Mpa, and the dwell time is 30 s;

(7) Discharging glue and sintering

The main purpose of the rubber discharge is to remove the binder (PVA) added during granulation, and the rubber discharge process is as follows: placing the molded ceramic sample into a muffle furnace, heating to 550 ℃ at a heating rate of 1.5 ℃/min, and preserving heat for 2 h; the purpose of sintering is to enable the grains of the sample to fully grow and improve the density of the sample; in the experiment, in order to reduce volatilization of V element, a buried firing method is adopted to sinter a sample, namely the sample after glue discharge is placed in an alumina crucible, powder with the same components is added to cover the sample, the temperature is increased to the sintering temperature at the heating rate of 5 ℃/min, and the heat preservation time is 6 h;

(8) Polishing and hot etching of samples

In order to obtain clear microstructure morphology, grinding and polishing the sintered ceramic sample on a polishing machine, and placing the polished sample into a high-temperature muffle furnace for hot corrosion; the heating rate of hot corrosion is 3 ℃/min, the hot corrosion temperature is lower than the sintering temperature of 80 ℃, and the heat preservation time is 40 min.