US-20260128221-A1 - MULTILAYER CERAMIC CAPACITOR

US20260128221A1US 20260128221 A1US20260128221 A1US 20260128221A1US-20260128221-A1

Abstract

A multilayer ceramic capacitor includes a capacitor body having a dielectric layer and an internal electrode layer, and an external electrode disposed on an outer surface of the capacitor body. The dielectric layer contains a plurality of dielectric grains, at least one of which has a core-shell structure including a core portion and a shell portion that surrounds at least part of the core portion. The dielectric grain includes barium (Ba), titanium (Ti), and rare-earth elements including lanthanum (La). In a measurement region extending from the interface between the core and shell portions to a depth of about 5 nm into the shell portion, an absolute value of the concentration gradient of lanthanum (La) is approximately 0.12 to 0.58 parts by mole per nanometer, based on 100 parts by mole of titanium (Ti).

Inventors

Jehee Lee
Jiseop Oh
Jihyun Lee
Hyungjoon JEON
Jeong Ryeol Kim

Assignees

SAMSUNG ELECTRO-MECHANICS CO., LTD.

Dates

Publication Date: 20260507
Application Date: 20250609
Priority Date: 20241105

Claims (17)

1 . A multilayer ceramic capacitor, comprising a capacitor body including a dielectric layer and an internal electrode layer, and an external electrode disposed on an outer surface of the capacitor body, wherein the dielectric layer comprises a plurality of dielectric grains, at least one of the plurality of dielectric grains has a core-shell structure including a core portion and a shell portion surrounding at least a portion of the core portion, wherein the dielectric grain having the core-shell structure comprises barium (Ba), titanium (Ti), and rare-earth elements including lanthanum (La), and in a measurement region from an interface between the core portion and the shell portion to a depth of 5 nm from the interface toward the shell portion, an absolute value of a concentration gradient of lanthanum (La) is 0.12 part by mole/nm to 0.58 part by mole/nm based on 100 parts by mole of titanium (Ti).
2 . The multilayer ceramic capacitor of claim 1 , wherein in a TEM-EDS (transmission electron microscopy-energy dispersive spectroscopy) line analysis for a long-axis straight section passing through a center of the dielectric grain having the core-shell structure, the core portion is a region in which lanthanum (La) is less than 0.8 part by mole based on 100 parts by mole of titanium (Ti), and the shell portion is a region in which lanthanum (La) is 0.8 part by mole or more based on 100 parts by mole of titanium (Ti).
3 . The multilayer ceramic capacitor of claim 1 , wherein lanthanum (La) has a higher molar content in the shell portion than in the core portion.
4 . The multilayer ceramic capacitor of claim 1 , wherein in the shell portion, a content of lanthanum (La) is 0.8 part by mole or more and 2.0 parts by mole or less based on 100 parts by mole of titanium (Ti).
5 . The multilayer ceramic capacitor of claim 1 , wherein the rare-earth elements further comprise at least one auxiliary element selected from a group consisting of scandium (Sc), yttrium (Y), neodymium (Nd), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), ytterbium (Yb), and lutetium (Lu).
6 . The multilayer ceramic capacitor of claim 1 , wherein the rare-earth elements further comprise auxiliary elements including yttrium (Y), terbium (Tb), and dysprosium (Dy).
7 . The multilayer ceramic capacitor of claim 1 , wherein the capacitor body comprises an active region in which the dielectric layer and the internal electrode layer are alternately disposed, and in a central region having a horizontal length corresponding to ⅙ of a total horizontal length of the active region each facing in a direction perpendicular to a stacking direction from an exact center of the active region, and a vertical length corresponding to ⅙ of a total vertical length of the active region each facing in the stacking direction from the exact center of the active region, an average size of the dielectric grains having the core-shell structure is 10 nm or more and less than 130 nm.
8 . The multilayer ceramic capacitor of claim 7 , wherein in the central region, an average size of the core portion is 35% to 67.3% of the average size of the dielectric grains.
9 . A multilayer ceramic capacitor, comprising a capacitor body including a dielectric layer and an internal electrode layer, and an external electrode disposed on an outer surface of the capacitor body, wherein the dielectric layer comprises a plurality of dielectric grains, at least one of the plurality of dielectric grains has a core-shell structure including a core portion and a shell portion surrounding at least a portion of the core portion, wherein the dielectric grain having the core-shell structure comprises barium (Ba), titanium (Ti), and rare-earth elements, and the rare-earth elements comprise lanthanum (La); and at least one auxiliary element selected from a group consisting of scandium (Sc), yttrium (Y), neodymium (Nd), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), ytterbium (Yb) and lutetium (Lu), and in a measurement region from an interface between the core portion and the shell portion to a depth of 5 nm from the interface toward the shell portion, an absolute value of a total concentration gradient of the rare-earth elements is 0.12 part by mole/nm to 0.58 part by mole/nm based on 100 parts by mole of titanium (Ti).
10 . The multilayer ceramic capacitor of claim 9 , wherein in a TEM-EDS (transmission electron microscopy-energy dispersive spectroscopy) line analysis for a long-axis straight section passing through a center of the dielectric grain having the core-shell structure, the core portion is a region in which lanthanum (La) is less than 0.8 part by mole based on 100 parts by mole of titanium (Ti), and the shell portion is a region in which lanthanum (La) is 0.8 part by mole or more based on 100 parts by mole of titanium (Ti).
11 . The multilayer ceramic capacitor of claim 9 , wherein a total content of the rare-earth elements has a higher molar content in the shell portion than in the core portion.
12 . The multilayer ceramic capacitor of claim 9 , wherein in the shell portion, a total content of the rare-earth elements is 1.2 parts by mole or more and 5.5 parts by mole or less based on 100 parts by mole of titanium (Ti).
13 . The multilayer ceramic capacitor of claim 9 , wherein the capacitor body comprises an active region in which the dielectric layer and the internal electrode layer are alternately disposed, and in a central region having a horizontal length corresponding to ⅙ of a total horizontal length of the active region each facing in a direction perpendicular to a stacking direction from an exact center of the active region, and a vertical length corresponding to ⅙ of a total vertical length of the active region each facing in the stacking direction from the exact center of the active region, an average size of the dielectric grains having the core-shell structure is 10 nm or more and less than 130 nm.
14 . The multilayer ceramic capacitor of claim 13 , wherein in the central region, an average size of the core portion is 35% to 67.3% of the average size of the dielectric grains.
15 . The multilayer ceramic capacitor of claim 9 , wherein the rare-earth elements comprise La, Y, Tb, and Dy.
16 . The multilayer ceramic capacitor of claim 15 , wherein a total content of La, Y, Tb, and Dy has a higher molar content in the shell portion than in the core portion.
17 . The multilayer ceramic capacitor of claim 15 , wherein in the shell portion, a total content of La, Y, Tb, and Dy is 1.2 parts by mole or more and 5.5 parts by mole or less based on 100 parts by mole of titanium (Ti).

Description

CROSS-REFERENCE TO RELATED APPLICATION This application claims priority to and the benefit of Korean Patent Application No. 10-2024-0202230 filed in the Korean Intellectual Property Office on Dec. 31, 2024, and Korean Patent Application No. 10-2024-0155174 filed in the Korean Intellectual Property Office on Nov. 5, 2024, the entire contents of which are incorporated herein by reference. BACKGROUND (a) Technical Field The present disclosure relates to a multilayer ceramic capacitor. (b) Description of the Related Art As electronic components using a ceramic material, there are a capacitor, an inductor, a piezoelectric element, a varistor, a thermistor, and the like. Among ceramic electronic components, a multilayer ceramic capacitor (MLCC) may be used in various electronic devices due to advantages such as a small size, a high capacitance, an easy mounting feature, and the like. For example, a multilayer ceramic capacitor (MLCC) may be used in a chip type condenser mounted on a board of several electronic products such as image devices, for example, liquid crystal displays (LCD), plasma display panels (PDP), or the like, computers, personal portable terminals, smartphones, and the like, to serve to charge or discharge electricity therein or therefrom. Recently, a technology has been proposed to reduce the thicknesses of the dielectric layer and internal electrode layer to achieve ultra-high capacitance in ultra-small multilayer ceramic capacitors. Additionally, design research is being conducted to achieve uniform resistance distribution by controlling the grain size and distribution within the dielectric layer. SUMMARY An embodiment provides a multilayer ceramic capacitor having excellent DC bias characteristics. An embodiment provides a multilayer ceramic capacitor including a capacitor body including a dielectric layer and an internal electrode layer, and an external electrode disposed on an outer surface of the capacitor body, wherein the dielectric layer includes a plurality of dielectric grains, at least one of the plurality of dielectric grains has a core-shell structure including a core portion and a shell portion surrounding at least a portion of the core portion, the dielectric grain having the core-shell structure includes barium (Ba), titanium (Ti), and rare-earth elements including lanthanum (La), and in a measurement region from an interface between the core portion and the shell portion to a depth of about 5 nm from the interface toward the shell portion, when measured from the interface toward the shell portion, an absolute value of a concentration gradient of lanthanum (La) is about 0.12 part by mole/nm to about 0.58 part by mole/nm based on 100 parts by mole of titanium (Ti). In a TEM-EDS (transmission electron microscopy-energy dispersive spectroscopy) line analysis for a long-axis straight section passing through a center of the dielectric grain having the core-shell structure, the core portion may be a region in which lanthanum (La) is less than about 0.8 part by mole based on 100 parts by mole of titanium (Ti), and the shell portion may be a region in which lanthanum (La) is about 0.8 part by mole or more based on 100 parts by mole of titanium (Ti). Lanthanum (La) may have a higher molar content in the shell portion than in the core portion. In the shell portion, a content of lanthanum (La) may be about 0.8 part by mole or more and about 2.0 parts by mole or less based on 100 parts by mole of titanium (Ti). The rare-earth elements may further include at least one auxiliary element selected from scandium (Sc), yttrium (Y), neodymium (Nd), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), ytterbium (Yb), and lutetium (Lu). The rare-earth elements may further include auxiliary elements including yttrium (Y), terbium (Tb), and dysprosium (Dy). The capacitor body may include an active region in which the dielectric layer and the internal electrode layer are alternately disposed, and in a central region having a horizontal length corresponding to about ⅙ of a total horizontal length of the active region each facing in a direction perpendicular to a stacking direction from an exact center of the active region, and a vertical length corresponding to about ⅙ of a total vertical length of the active region each facing in a stacking direction from an exact center of the active region, an average size of the dielectric grains having the core-shell structure may be about 10 nm or more and less than about 130 nm. In the central region, an average size of the core portion may be about 35% to about 67.3% of the average size of the dielectric grains. Another embodiment provides a multilayer ceramic capacitor including a capacitor body including a dielectric layer and an internal electrode layer, and an external electrode disposed on an outer surface of the capacitor body, wherein the dielectric layer includes a plurality of dielectric grains, at least one of the p