php json_encode返回null

Array
(
    [sEcho] => 1
    [iTotalRecords] => 7521
    [iTotalDisplayRecords] => 1
    [aaData] => Array
        (
            [0] => Array
                (
                    [0] => Nordic Capital Buys SiC Processing
                    [1] => 2010-06-21/nordic-capital-buys-sic-processing
                    [2] => PEHub Media
                    [3] => Business
                    [4] => completed
                    [5] => Nordic Capital has acquired a 70% stake in SiC Processing AG, a German industrial recycling company, from Frog Capital. No sale price was disclosed.  SiC Processing’s founding family retains a 25% holding, while former lead investor Zouk Ventures retains a 5% stake.

                    [6] => Admin, China, Frog Capital, Germany, Italy, Iyad Omari, Manufacturing, Norway, PEHub Media, Photovoltaic Wafer Manufacturing, Renewable Energy, Semiconductor, United States
                )

        )

)

echo json_encode($myArr);

{“sEcho”:“1”,“iTotalRecords”:7521,“iTotalDisplayRecords”:“1”,“aaData”:[[” 北欧资本收购碳化硅加工公司</a></div>“,” 无效的 ," Admin,中国,Frog Capital,德国,意大利,Iyad Omari,制造业,挪威,PEHub Media,光伏晶圆制造,可再生能源,半导体,美国]]}

请注意完成后字符串中间的null

为什么会这样,我需要执行什么转义/操作才能对其进行编码?

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